365 Days of Climate Awareness 140 – 2003 State of the World Climate

 

2003 World Climate Data

• Atmospheric CO₂ concentration: 375.15ppm, +2.56 ppm from 2002
• Surface air temperature anomaly: +0.65°C/1.15°F, 12^th all-time 1880-2021
• Precipitation below 1961-1990 global average
•  ENSO: Moderate El Niño till April; neutral for the rest of the year

Global Conditions

•  Above-average temperatures: western Arctic Ocean basin; South America; southeastern China; Russia; Australia
•  Below-average temperatures: European Russia
• Drought: northeastern South America; southeastern Africa; southeastern China; southeastern Australia; New Zealand; southern Asia
•  Extreme rain: Argentina; northwestern South America; Algeria; Tunisia; the Sahel (central Africa south of the Sahara); Kenya; Yellow River basin;  southwestern Asia (parts of Afghanistan and Pakistan, Iran)

2003 Significant Global Events  Larger version

Though the El Niño event ended in April, its temperature effects were felt through much of the year. To date, for global air temperature, 2003 was second only to 1998. While boreal spring (austral fall) rain patterns were typical for an El Niño, the North Atlantic (boreal summer and fall) hurricane season was extremely active. Southern and western Australia, recovering slowly from 2002’s record drought, experienced a series of serious bush fires started mostly by lightning.

Following an El Niño event, typically conditions revert to La Niña, with resumed easterly trade winds bringing cooler surface water west across the Pacific tropics. However, in the months of May and June strong westerly tropical winds brought the warmer waters there to the east, dissipating any potential spread of cold water. This did not result in a full El Niño event, but did restore some of El Niño’s typical atmospheric temperature and rain patterns.

Northern hemisphere snow cover was slightly above the 1961-1990 average, with winter (2002-03) extents within the top ten for the past 30 years, and July snow cover at a record low.  Arctic summer sea ice extent had been on a downward trajectory since the late 70’s, and after 2002’s record low summer extent, recovered slightly in 2003 to roughly the same area as 2001.

Tomorrow: 2004 State of the Climate, North America and Europe.

Be brave, and be well.

AMS Annual State of the Climate Reports

365 Days of Climate Awareness 139 – 2003 State of the Climate, North America and Europe

2003 US Climate Data

• Global atmospheric CO₂ concentration: 375.15 ppm, +2.56 ppm from 2002
• Average air temperature: 54.9°F, 24^th all-time 1894-2021
• Average precipitation: 28.13”, 25^th driest 1894-2021
• Tornadoes: 1384, above the 1991-2010 average 1228
• 16 named tropical cyclones: 7 became hurricanes, 3 major (winds > 111 mph, 3-5 Saffir-Simpson)
• ENSO: Moderate El Niño through April, neutral from then till year’s end

North American Conditions

• Warmer than average: almost all of Canada; western US
• Drought: northeastern Mexico, western US, Canadian prairies; up to 33% of the US in midsummer
• Precipitation: eastern US wetter than average; rainfall in Canada 1.8% above average; western US below average
• Wildfire: 1.5 x 10⁶ hectares (ha) (3.7 x 10⁶ acres) burned, 80% of 1992-2002 average.
  
  
  
  
  

State-by-state historical rankings, 2003 temperature.

The 1961-1990 average for named storms in the North Atlantic is 9.8. The 2003 total of 16 is close to double that, and continued the 1990’s trend of highly active hurricane seasons. NOAA characterizes seasonal hurricane activity with the Accumulated Cyclone Energy (ACE) index, which estimates wind energy by squaring the hourly sustained wind speed for every tropical storm/hurricane. The ACE is the sum total of all squared wind speeds, across all storms, for the season. 2003’s ACE was 174.75 x 10⁴ kt², almost exactly double the 1951-2000 median value of 87.5 x 10⁴ kt².

State-by-state historical rankings, 2003 precipitation.

The El Niño which began the year, and the negative NAO (smaller Atlantic pressure anomalies meaning a lower pressure gradient from south to north) combined to bring consistent precipitation to the east coast and southeastern region of the US, including a snowy 2002-03 winter. Snowfall in the west was not far below normal, as opposed to the extreme warmth and dryness of the summer. Mexico likewise had drought conditions for much of the year, though late-season tropical storms alleviated this in the central eastern region of the country.

2003 Percentage of US very warm vs. very cold.

Europe experienced above-average temperatures all year, with record-breaking heat through the summer months, especially in the western countries. This heat wave resulted more than 11,000 deaths in France alone. Alpine glaciers lost an estimated 3 m of ice thickness, nearly twice the 1998 record for melting. At the same time, precipitation was well below average.

2003 Percentage of US very dry vs. very wet.

Tomorrow: 2003 State of the World Climate.

Be brave, and be well.

365 Days of Climate Awareness 138 – Teleconnections

With the State of the Climate posts regularly pointing out the global effects of ENSO, it’s useful to take a step to the side for the moment to look at the concept and some of the mechanics involved. Long-distance effects—generally on the scale of a thousand or more kilometers (about 620 miles)--through the atmosphere are called “teleconnections”.

El Niño teleconnections throughout North America.

A teleconnection is not merely the spread of a single state or condition through the atmosphere. It is a series of effects—a cascade or dominos are good analogies—from a place of origin to a geographically remote location. To contrast some major effects of the ENSO cycle: during an El Niño episode, the warmer Pacific water leads to warmer, low-pressure air above it, and the stratospheric jet stream runs more directly west-to-east. This brings warmer weather to western Canada and the Pacific Northwest, and increased rain and storm activity across the southern United States. During a La Niña, however, the cooler ocean water leads to colder, higher-pressure air over the North Pacific, which diverts the polar jet stream there northward. That causes the jet stream farther east to be diverted to the south, bringing Arctic cold, dry air down into the United States and drier conditions to the southern part of the country.

La Niña teleconnections throughout North America.

As another example, a positive phase of the North Atlantic Oscillation (NAO), where northerly (Iceland) air pressure is low, and subtropical (Azores) air pressure is high, is correlated with high temperatures in the eastern US and northern Europe, and colder temperatures in southern Europe, the Mideast, and sometimes Russia. Meanwhile, a negative NAO (high arctic pressure, low subtropical) leads to cold weather in the southeastern US and northern Europe, and warm, wet weather in the Mideast. As with ENSO, the changes in air pressure direct the jet stream which controls weather patterns.

Generally we observe these teleconnections statistically, before we develop an analytical understanding. A further horizon in the study of climate science is the interaction between major oscillations, such as ENSO and the NAO, and their influence on each other, as well as their combined, sometimes opposed effects.

Tomorrow: 2003 state of the climate, North America and Europe.

Schematic of the North Atlantic Oscillation.

Be brave, and be well.

365 Days of Climate Awareness 137 – 2002 State of the World Climate

2002 World Climate Data

• Atmospheric CO₂ concentration: 372.59 ppm, +2.02 ppm from 2001
• Surface air temperature anomaly: +0.56°C/1.01°F, 16^th all-time 1880-2021
• Precipitation below 1961-1990 global average
• ENSO: neutral at year's beginning, El Niño by September

Global Conditions

• Above-average temperatures: Northern Hemisphere +0.63°C/1.13°F over 20^th century average; ocean surface +0.42°C/0.76°F over 20^th century average; Paraguay; Bolivia; Russia;
• Drought: Australia (esp. eastern); Indian monsoon (-19%); north coast of China; Mexico; parts of Central America; southern Brazil; eastern Africa; western Russia; northeast China; central Asia; Australia (as El Niño emerged)
• Extreme rain: southeast Asia; Japan; central and southern China; Taiwan; Philippines; eastern and northern Brazil; Argentina; Urugay; central and eastern Russia
  
  
  
  Larger version

Climate science features at times endless sequences of chicken-and-egg questions. Where do we stop in looking for causes for El Niño and La Niña events, when the sea surface temperatures which mark them are both effects and causes in a worldwide network of activity in the ocean and atmosphere? The point is not to throw our hands up in futility but rather go on analyzing what is happening, and what its antecedents and consequences are.

ENSO is one of the clearest examples we have on the planet of a large phenomenon which impacts the whole climate system, and is both caused by and generates chains of events on different timescales. Each interaction of these several different chains of events is unique. ENSO is an important indicator for global weather patterns and we are continuing to learn not only more specific detail about how it operates but also its role in historical trends.

In a year like 2002, with neutral ENSO giving way to El Niño conditions, a number of signs appear in the ocean and atmosphere months before the relaxation of the easterly trade winds and the eastward flow of warm surface water. The ocean and atmosphere in the Pacific tropics mirror each other, as warm water and air gather in the equatorial region. The tropical thermocline, denoted by the 20°C isotherm in the ocean, deepens from 100 to 200 m or more, signaling buildup of warm water at the surface. Meanwhile a dome of warm air builds over the zone of deepening warm ocean water. These are reliable predictors of an approaching El Niño.

Tomorrow: teleconnections.

Be brave, and be well.

365 Days of Climate Awareness 136 – 2002 State of the North American and European Climate

2002 US Climate Data

• Global atmospheric CO₂ concentration: 372.59 ppm, +2.02 from 2001
• Average air temperature: 54.9°F, 22^nd all-time 1894-2021
• Average precipitation: 26.05”, 25^th driest 1894-2021
• Tornadoes: 836, well below the 1991-2010 average 1228
• 12 named tropical cyclones: 4 became hurricanes, 2 major (winds > 111 mph, 3-5 Saffir-Simpson)
• ENSO: neutral through July, El Niño by year’s end

North American Conditions

• Temperature: northeast and southwest particularly warm; no state significantly below 20^th century ave.; Canada warmer than ave. for 10^th straight year
• Above average dryness: western half of the US; Colorado record dryness during December; central and western Canada; 23% of US in drought in early 2002; 39% by July
• Precipitation: eastern US wetter than average
• Wildfire: second-worst US season to date (Midwest and western states)

Snowfall in Canada and the US was below average, due to above-average temperatures in the air, though the warmer-than-usual Great Lakes contributed to increased localized snowfall. Dry conditions persisted in the Great Plains—drawing comparisons to the drought of 1988, and even to the Dust Bowl era—but the Gulf Coast and eastern states received enough rain from a series of tropical storms to relieve the drought and depress the fire hazard. Drought persisted throughout Canada and led to one of the worst growing seasons in the country’s history.

The 2002 North Atlantic hurricane season featured below average activity, with nearly 75% of that occurring with three September hurricanes in the Caribbean. This correlates with the emergence of El Niño, which affects wind patterns across the South American and Caribbean tropics, such as by the prevalence of upper-level westerly (eastwardly-blowing) winds which increase shear and impede hurricane formation. In September, however, hurricane Gustav, which had weakened to a tropical storm, regained hurricane strength from the water off the coast of the eastern US, and hit Nova Scotia as a newly-reformed hurricane. This and other storms contributed to a wet end to the year for maritime Canada.

Europe experienced above-average temperatures throughout the year, with the UK and Ireland have near-record-warmth. Scandinavia experienced one of its warmest summers on record, though the fall brought much cooler temperatures there and to western Russia. Precipitation was below average throughout the region, with only parts of Norway, Sweden and Iceland receiving greater-than-average snow and rainfall on the year. Despite that, the summer brought flooding throughout much of the central part of the continent.

 

Tomorrow: 2002 state of the world climate.

Be brave, and be well.

365 Days of Climate Awareness 135 – 2001 State of the World Climate

2001 Global Climate Data

• Atmospheric CO₂ conc.: 370.57 ppm, +1.61 ppm from 2000
• Surface (air & ocean) temp. anomaly: +0.51°C (0.92°F) over 1880-2000 ave
• Overland precipitation: -1.9% from 1961-1999 average
• ENSO: from La Niña to neutral

Departures (>10% difference) from 1961-1990 Average

• Warmth: southern Australia; New Zealand
• Cold: Siberia, eastern Russia, Mongolia—winter;
• Dryness: Brazil (austral summer); southern Africa; African horn; Cambodia; Vietnam; Iran; Pakistan; Afghanistan; Tajikistan; Uzbekistan; Turkmenistan; southern Australia; southwest Pacific
• Precipitation: South American Pampas (Uruguay, parts of Argentina and Brazil); northern
• Australia
  
  
  
  

At the time, 2001 ranked second behind 1998 as the second-warmest for global surface air temperature (from 1880 forwards). Now it ranks 20^th (1998 is tied for 17^th). As a look forward—every year from the 1998-2013 period, falsely labeled a global warming “pause” by deniers–appears in the top 20 all-time. Warmer overland temperatures occurred largely in the tropics and northern hemisphere, where positive anomalies were greater than in the southern extratropics (>23.5° S).

 

World climate events, 2001.  Larger version

Northern hemisphere snow cover was below average for the fifth consecutive year, despite extreme cold in northern and eastern Asia and extremely heavy snowfalls in Mongolia and northern China. Snow cover, like sea ice, precipitation, drought and other climate indicators, is highly variable from year to year, having many influencing factors. Snowmelt in areas such as Alaska’s north slope (between the Brooks range and the Arctic Ocean) is occurring earlier by the year.

Radiative forcing—the heating contribution per year in watts per meter squared (W/m²/year) of each individual greenhouse gas, increased 0.026 W/m² in 2001, almost entirely due to carbon dioxide. From the end of the last glaciation to the beginning of the industrial age (1750), radiative forcing has increased by roughly 2.8 W/m², of which CO₂ is responsible for about half. (2021’s CO₂ concentration of 370.57 ppm is roughly one-third higher than the interglacial average.) Though the Antarctic ozone hole continues to exist and affect temperatures in the stratosphere, it is not growing at the rate that it did before. Both that and the decline of CFCs in the radiative forcing budget are the result of successful regulation.

Tomorrow: 2002 state of the climate, North America.

Be brave, and be well.

Columbia University Annual Temperature Anomaly Rankings

Columbia University Global Temperature Monitoring Page

American Meteorological Society (AMS) Climate Assessment Report page

365 Days of Climate Awareness 134 – 2001 State of the Climate, North America and Europe

2001 US Climate Data

• Global average atmospheric CO2 concentration: 370.57 ppm, +1.61 ppm over 2000
• Mean air temperature: 55.3°F, +1.6 over 1884-2021 ave, 16^th warmest as of 2021
• Mean precipitation: 26.6”, -0.93” from 1894-2021 ave, 35^th driest
• 8 very strong tornadoes (winds ≥ 158 mph, category F3-F5), well below average of 38
• 15 named tropical storms: 9 became hurricanes, 4 major (winds ≥ 111 mph, cat. 3 or higher)

North American Conditions

• Excessive rain: upper Midwest and Mississippi valley
• Drought: 15% of the country in early 2001, peak of 20% by October: southern Great Plains, western US, eastern seaboard (later in the year), Hawaii
• Wildfires: Great Basin (parts of Nevada, Utah, California, Idaho, Oregon, Wyoming), Pacific Northwest, East Coast
• Above-average overland air temperatures, particularly in Canada

• 
  2001 US very hot vs very cold, area percentage

With the fading of La Niña conditions to a neutral state by midyear, the southern US was released from several years’ drought. Several late-year storms from the Pacific provided drought relief along the Pacific Northwest coast. Tropical Storm Allison brought significant flooding to the Gulf and East Coasts, hugging the coastline and continuing to derive heat and moisture from the ocean. Allison ended its existence causing $5B in damage, the most expensive storm to date in US history.  While no hurricanes impacted the United States, for the first time in recorded history three of them formed in the North Atlantic in November.

2001 US very wet vs very dry, area percentage

Late winter brought several large snowfalls to the northeast, leading to an above-average spring snowpack. West of the Appalachians, this excess snow combined with heavy spring rains to produce flooding in the upper Mississippi, throughout Minnesota and Wisconsin.

Europe outside of Scandinavia experienced above-average temperatures, with parts of Germany averaging as much as 4°C (7.2°F) above. Southern Europe, the Mediterranean coasts and the UK were drier than normal, while central and northern Europe and Scandinavia were wetter. However, southern and eastern Europe ended the year with stormy weather due to a southward shift in low pressure.

Tomorrow: 2001 state of the world climate.

A peaceful holiday to everyone. While pain and loneliness continue to exist in this world, we can try to overcome them with kindness and love. Be well, all.

365 Days of Climate Awareness 133 – 2000 State of the World Climate

2000 World Climate Data

Global atmospheric CO2 concentration: 368.96 ppm, +1.16 over 1999

Global mean air temperature anomaly: +0.76°C over 20^th c. ave, 26^th warmest 1894-2021

Global precipitation 3.9% greater than 1961-1990 mean: 3^rd wettest year to date

* * *

2000 was another persistently La Niña year, though the intensity of the episode’s coldness was less during the first nine months. Precipitation patterns were consistent with other La Niña episodes: heavy rains in Indonesia, the eastern tropical Indian Ocean, southeastern Asia, northern Australia, and the western and central South Pacific, while the western and central tropical Pacific were drier than usual. Land temperatures were above the 30-year mean (1961-1990), particularly in the extratropical northern hemisphere. Many parts of North America and Eurasia were as much as 4°C above average.

\Northern hemisphere snow cover was, for the fourth consecutive year, below average, a trend which had largely held since the late 1980’s. Snow deficits have tended to be lower in late winter. The Indian monsoon (June-September) was slightly wetter than average but followed an unusually dry spring. Mongolia experienced a very harsh winter, with more snow and colder temperatures than average, badly damaging the livestock industry. Meanwhile, western Asia from Iran to Afghanistan was affected by drought.

The rainy season in southern Africa was particularly intense, typical for a La Niña year. Farther north, in the horn (Kenya, Ethiopia and Somalia) there was widespread drought, the worst since the mid-80’s. Rainfall in western Africa was close to average levels. Rainfall was well above average in northern South America, particularly in the Amazon Basin. Southern South America experienced a stretch of extremely cold winter (June-Sepember) weather, as Antarctic air stretched north over the continent in a manner like the fluctuations of the Polar Vortex in the north.

Tomrorow: 2001 state of the US climate.

Be brave, and be well.

365 Days of Climate Awareness 132 – 2000 State of the Climate, North America & Europe

2000 US Climate Data

Global atmospheric CO2 concentration: 368.96 ppm, +1.16 ppm from 1999

Mean annual temperature 55.5°F, +1.7°F over 20^th c. ave, 12^th warmest 1894-2021

16 very strong tornadoes (wind >158 mph, scale F3-F5), below long-term mean of 38

14 named storms: 9 became hurricanes, 3 severe (wind ≥ 130 mph) (vs. average 9-7-2)

* * *

2000 was another La Niña year, and brought an abnormally warm winter and spring to the United States, particularly in the southern and western parts of the country. The Midwest and northeast experienced a cooler second half of the year. November and December became very cold, with more than 50% of the country experiencing very cold temperatures.

US Temperature Anomalies, 2000

Most of the country had drought or dry conditions, but the Great Lakes and northeast regions received more-than-average precipitation. According to the Palmer Index, 16% of the country was in drought in January, peaking at 36% in August. Meanwhile, 5% was extremely wet. In summer, wildfires in the western states destroyed 7.3 million acres of forest. Dry conditions in that region had persisted since 1999. The worst droughts occurred throughout the Deep South (Alabama, Florida, Georgia, Louisiana, and Mississippi).

US Precipitation, 2000

Southeastern Europe experienced extremely high temperatures followed by water shortages in late summer. Meanwhile, precipitation in Britain and western Europe fluctuated between dryness in the first three months of the year, to extreme amounts in the second three months, back to dryness in summer, followed by a wet and stormy autumn across most of Europe.

Tomorrow: 2000 state of the world climate.

Be brave, and be well.

365 Days of Climate Awareness 131 – State of the World Climate, 1999

1999 World Climate Data

Global CO₂ concentration, 367.8 ppm, +2.1 over 1998

Average global temperature anomaly, +0.79°C over 20^th c. ave, 25^th warmest 1894-2021

 * * *

1999 featured a persistent La Niña state in the Pacific Ocean, leading to a lower average global sea surface temperature, though air temperatures remained elevated. The run of well-above-average air temperatures continued from its start in 1977, though the decade of the 1990’s established a new, consistently higher departure from the century mean. In 1998 began a phase where global air temperatures did not continue rising at the same continual pace of the previous decade. It was to last through 2013 and was cynically, and very inaccurately, called a “pause”. In fact global air temperature continued to rise, albeit more slowly, while ocean temperatures rose considerably. In effect, global temperature rise was simply shifting gears, where heat uptake occurred in a different part of the system.

 La Niña helped produce lower temperatures throughout the tropics, while both northern and southern extratropics (>23.5° N/S), including Eurasia, northern and southern Africa (outside of the tropics) were 1°C or more hotter than average. Precipitation, consistently with other La Niña years, was higher than normal in Indonesia, the tropical Indian, western, and south central Pacific Oceans. Central China, the Amazon basin and northern South America, and northern Australia.

The rains in China produced catastrophic floods in the Yangtze river valley which displaced more than 2 million people. Deadly floods also occurred in Venezuela, and an historically strong cyclone in the Bay of Bengal caused a storm surge in Bangladesh which killed more than 10,000. Heavy rains in Vietnam displaced 1 million and killed 700.

Tomorrow: 2000 state of the climate, US and Europe.

Be brave, and be well.

365 Days of Climate Awareness 130 – State of the Climate, North America and Europe, 1999

1999 US Climate Data

Global CO₂ concentration, 367.8 ppm, +2.1 over 1998

Average temperature: 55.5, +1.7 over 20^th century mean, 15^th warmest 1894-2021

Average precipitation: 26.74”, 0.85” less than 20^th century mean (37^th driest 1894-2021

12 named storms: 8 became hurricanes, 5 intense (≥3 Saffir-Simpson) (20^th c. aves: 10-5-2)

1351 tornadoes, below the 20^th century average of 1383

* * * 

1999 was a year of persistent, moderately strong La Niña conditions. Central America and the Caribbean were rainier than usual in the second half of the year, and September especially featured intense hurricane activity. As is common, the active North Atlantic hurricane season was balanced by a comparatively inactive northeast Pacific storm season. This Pacific-Atlantic dipole is a function of large-scale wind patterns. Wind shear—changes in wind speed and direction as you move up through the atmosphere—diminishes hurricane activity. The Atlantic and Pacific tend to oppose each other. In years, like 1999, when there is little wind shear in the Atlantic, there is much more in the Pacific, and vice versa.

1999 US regional average temperatures.  Larger version plus context

The Pacific northwest and down the coast to California received intense precipitation in the winter of 1998-1999. The American southwest also experienced wet monsoonal conditions, as is typical after a La Niña winter. La Niña usually results in reduced mountain snowfall in the southern Rockies. This leads to rapid warming of the land in late spring and a stronger monsoonal circulation.

1999 US regional precipitation.  Larger version plus context

29 US states experienced serious drought, particularly the northeast, and central region (upper Midwest down to Texas). Midwestern crops suffered badly, but the drought was replaced in the northeast by extremely rainy weather in the latter half of the year.

In winter 1999 Europe experienced a series of severe wind storms, with wind speeds in excess of 120 mph (category 3 Saffir-Simpson) across Denmark, Germany, France and Switzerland. These winds were associated with a positive NAO phase, with higher than average air pressure in the Azores and lower than average air pressure over Greenland. Early 1999 winter snowfall in the Alps and eastern Europe was well above average, but throughout most of the year, Europe had above-normal temperature.

Tomorrow: 1999 state of the world climate.

Be brave, and be well.

365 Days of Climate Awareness 129 – 1998 State of the World Climate

1998 Global climate data

Atmospheric CO₂ concentration: 365.70 ppm, +2.65 over 1997

Mean temperature anomaly: 1.17°F above 20^th c. mean (11^th warmest year 1900-2021)

1998 began with a very strong El Niño and ended with a very strong La Niña, and both phases were joined by global temperature trends. The warm, El Niño phase of the year brought elevated temperatures globally. Record high temperatures at the time were set in both hemispheres. Further, both north and south tropics experienced record high temperatures, as well as the northern extratropics (>23.5° N latitude). Late in the year, with the Pacific Ocean in its cold La Niña phase, dry, cold air dominated the eastern Pacific, and global monsoons and the North Atlantic hurricane season picked up.

Northern hemisphere snow cover was the lowest in every single month except October for the period of 1972-1998 (due to varying length and spatial coverage of datasets, different measurable like temperature, CO₂, precipitation and snow cover among others, seldom have similar baselines. Uneven, at times highly uneven, coverage is one of the limitations of global climate science).

Mexico experienced a severe drought during the El Niño event. Likewise northern South America, except for coastal Ecuador Peru, was drier than normal at this time, and southern South America somewhat wetter. In late October and early November Hurricane Mitch, today considered the 7^th most powerful hurricane in history, formed in the Caribbean and devastated Honduras and Nicaragua, causing more than 11,000 deaths and, according to the president of Honduras, setting the country back economically 50 years.

India’s monsoon season went from average in the first (El Niño) part of the year to substantially wetter in the second (La Niña) half, though catastrophic rains killed thousands in Nepal and Bangladesh. The August rains also caused flooding in the Yangtze (one of the many rivers which drains the Himalaya, along with the Indus, Ganges, Brahmaputra, and Yellow).

Northern Africa’s weather is more closely related to the equatorial region known as the Intertropical Convergence Zone, the region between the northern and southern Hadley Cells (discussed in posts 36 and 125). A dry early phase of the year was followed by severe floods in Mali and Niger. South African weather is closely correlated to ENSO, and the same pattern held of a dry early and wet late year.

Tomorrow: 1999 State of the Climate, North America and Europe.

Be brave, and be well.

365 Days of Climate Awareness 128 – 1998 State of the Climate, North America and Europe

US climate data, 1998:

Global atmospheric CO2 concentration: 365.7 ppm, +2.65 above 1997

Average temperature: 55.9°F (+2.1°F anomaly above 20^th c. ave), 6^th warmest 1894-2021

Average rainfall: 33.89” (3.95” anomaly above 20^th c. ave), 6^th wettest (122^nd driest) 1894-2021

14 named cyclones, 9 becoming hurricanes, 3 major (>3 Saffir-Simpson, >130 mph winds)

1422 tornadoes, above the 20^th century average 1383

1998 began with a very strong El Niño, and ended with a very strong La Niña. There were 14 named North Atlantic cyclones, of which 9 became hurricanes, including Mitch, a historically strong storm which devastated Nicaragua and Honduras and impacted Florida as a tropical storm. Mitch ended its existence as the deadliest North Atlantic storm since 1780.

Warm temperatures across North America were associated with the early-year El Niño. 75% of the United States experienced warmer-than-usual temperatures, while only 1% was persistently cooler than usual. Late spring and early summer brought drought to the south and southeastern United States, leading to wildfires in Florida. During this time wet weather befell the north and northeast.

Snow cover was below average in North America throughout the entire year, whereas in eastern Europe conditions were snowier than usual. Throughout most of northern Europe, snow cover was low in the first half  of the year, and greater than average in the second half. Europe south of 60° was warmer than usual.

Tomorrow: state of the climate: Asia, South America, Africa and the southern hemisphere, 1998.

Be brave, and be well.

365 Days of Climate Awareness 127 – Return to Climate Annals

This is another post where I beg your pardon as readers, explain a previous false start, and begin again with a steadier approach (like I did in post #3 after plunging into really obtuse details about climate modeling to start the whole series). When I began a string of annals-type posts about the state of the US climate from 2010 forward, I hadn’t thought through what data to present, and how to present it. The result was a few willy-nilly posts which wouldn’t add up to much in terms of education. I needed to go into some background on extreme events—the frequent topic of annual and monthly reports—and develop the narrative framework.

So here I am again, about to unleash a run of climate annals on you, but in a more compact and comprehensive way, so you the readers will be able to make some useful comparisons between years and identify patterns. My primary goal in this entire 365 Days series is to help make people more interested and discerning observers of the climate and of reporting on it.

With tomorrow’s post, #128, I’ll begin the annals, starting with 1998. I go back that far because that’s the first year when NOAA began publishing its State Of The Climate monthly and annual reports. They’re brief but very informative. Like any annals, the reports were written at the time, not from a future perspective looking back. I attempt to put such a historical perspective on them, but will, to keep posts brief, still go year-by-year. Two posts will be devoted to each year: first, the US report, and then the global report. So to come from 1998 to the present will require 48 posts.

From there, I’ll be able to look a little more broadly at our recent climatic period, and some of the decadal-scale trends we’ve lived through in recent times, and then move onto where I began the entire series: on climate modeling, and how scientists try to look forward based on existing data and mathematical formulas.

This part of the series is, frankly, a learning exercise for me too. I studied oceanography in graduate school, and since then geology and ocean engineering. So the general topics and background explainers I spent most of the first hundred posts on were general knowledge I gained along the way. But moving now into specific climatic events, on both the national and global scale, is fresh synthesis for me too. It’s exciting!

But real excitement can’t obscure that we have a very real fight on our hands, to save our country and our global society from autocratic, profiteering bad actors who know and care nothing about the natural world and our place in it. Having fun along the way is no sin, but information and learning have to play a role in accomplishing real change.

Tomorrow: US state of the climate, 1998.

Be brave, and be well.

365 Days of Climate Awareness 126 – US Climate Normals

Popular science is full of hidden quantities. The boiling point of water, 100°C/212°F, assumes one standard atmosphere of pressure (1.013 bar). The boiling point varies proportionally with air pressure. At 10000 ft (3048 m) elevation, for example, water boils at 193°F/89.5°C (which is why performance climbers need pressure cookers to boil food). When you read or hear about the decibel level of sound, such as at an airfield or in a domed stadium, the decibel count is power (exponents) ratio of sound pressure level against a reference (usually 20 micropascals, mPa, considered the lower threshold of normal human hearing). That reference pressure is a type of datum: a fixed reference for other measurements.

Datums permeate science. In mapping, establishing datums such as the shape of the earth (the “reference ellipsoid”) and “sea level” is critical for giving useful depths and elevations. (Establishing “sea level”, otherwise known as the “geoid”, is a complicated and very important process.) The same is true in climate science. There are reference quantities used as the basis for comparison against other measured values, and these reference quantities are called “normals”.

Frequently, when looking at a map of temperature or precipitation anomalies, the map will state the datum for comparison (“pre-industrial”, i.e. 1750-1800; 1900-2000; etc.). But the climate is dynamic enough—variables such as temperature move steadily away from previous baselines—that resetting the baseline, resetting the datum, is useful. So the World Meteorological Organization (the WMO) has set up the rule that countries must publish new climate normal—averages of the previous 30 years’ meteorological data—every ten years.

This is to provide a rolling window of statistically useful comparison. 30 years is enough time to account for climate trends (the meteorological definition of climate is the 25-year average of weather), but short enough that the average values are closely comparable to the present day. The US’ latest set of climate normals, spanning 1990-2020, was published in May 2021. These normals will serve as the basis for meteorological anomaly maps for the next ten years.

The normals  are calculated carefully from weather stations across the country, accounting statistically for missing data points (if an instrument went down for any length of time) and biases (such as urban heat islands or proximity to other stations). Plots of the different normals over time, compared against a longer datum (such as the 20^th century) are very instructive: long-term weather averages compared to a much longer-term average: climate vs climate: gives a very robust view of climate change.

Tomorrow: resetting the year-by-year climate annals, beginning with 1998.

Be brave, and be well.