365 Days of Climate Awareness 231 – Africa’s Main Climate Change Issues

The mean air temperature in Africa has increased by about 1°C/1.8°F since 1901, slightly above the global land mean. Outside of the mountainous regions, temperature increases have occurred everywhere, if not uniformly (as much as 3°C/5.4°F in parts of the Sahel). Precipitation patterns are more complex. Rainfall has decreased everywhere except in the tropical rainforest zone around the equator, where seasonally it has increased.

Climate data is very sparse across the entire continent. Information on trends is limited, though predictive models are easier to find. Those models, based of course on the historical information, show a future consistent with the record from the 20^th and early 21^st centuries: warming and drying in the subtropics of Africa, and an expanded tropical zone.

Temperature anomaly trends by season, 1902-2014.

Precipitation anomalies by season, 1902-2014.

Agriculture in much of Africa is localized, relying on rain, not groundwater-fed irrigation systems. As a result African farms outside the tropics are especially vulnerable to drought. Decreased rainfall will also diminish livestock production, and hunting and fishing catch. Given the social tensions in parts of Africa and weakness of several of its governments, large climate disruption of food production could lead to huge social unrest and major migrations.

Köppen-Geiger zones, 1980-2016.

Köppen-Geiger zones, predicted, 2071-2100.

As the subtropical zones become hotter and drier, the habitable coastal zones on north and south have been increasingly squeezed, and that trend is likely to continue. The Sahara has grown to north and south since the early 1900’s and will almost certainly expand further. Africa’s present and future climate reality is severely constrained by water scarcity.

Tomorrow: introduction to South Africa.

Be brave, and be well.

365 Days of Climate Awareness 230 – Introduction to Climate Justice

In this series I have focused mostly on the physical aspects of climate change: the drivers, the mechanisms, the results. Implied has been much of the human impact, when I’ve referenced sea level rise in the islands, or increasingly erratic behavior of the jet stream, or otherwise. But society and economies are major aspects of this entire saga, both as cause and recipient. As an oceanographer and geologist, I have kept my focus mostly on the environment, veering now and then, only tentatively, into the world of economics or policy. I try to abide by Twain’s point about not revealing myself to be a fool.

Bangladesh: current, and with modeled 1- and 1.5-meter sea level rise.

But a look throughout the entire world at the impacts of global warming brings us very quickly to the concept of climate justice. My definition of “climate justice” is the balance of human rights against political and economic factors in climate change. As we tour the world and look at nations which are smaller, less wealthy, and physically more vulnerable to changes in climate, the injustice is obvious right away.

Per Capital Greenhouse Gas Emissions by Country, 2018

Tiny island nations like Kiribati or the Maldives, or even significantly larger ones like the Philippines, have gladly piggybacked on the world’s economic expansion, while not being main drivers of the expansion. And their relative lack of wealth and their physical situations leave them disproportionately exposed to global warming threats. Another example is Bangladesh, population 163 million, one of the poorer nations on earth, with rising sea levels and increasingly severe flooding. It stands to lose 10% of its land area with 1 m in sea level rise. It is a prime case of a poor country likely to produce large numbers of climate refugees.

Total Greenhouse Gas Emissions by Country, 2018

The practice of climate justice is to balance the responsibility for climate change with its impacts. Industrial leaders, with the highest aggregate, annual and per-capita greenhouse gas emissions, bear the greatest responsibility for this climate calamity. But while global warming impacts all countries, it doesn’t do so evenly. Smaller nations, those largely not responsible for creating the crisis, are much more easily destabilized by it. Any system of justice would address that disparity.

Total Historical Greenhouse Gas Emissions by Country, 1850-2021

There is at present little or no recourse. Last fall’s COP-26 in Glasgow, where the oil industry was better represented than any country, was the best chance of countries impacted by climate change to gain even non-binding pledges of action. They came away largely empty. The International Court of Justice, even when it rules on cases involving climate change, cannot compel any judgments. Simply put, small and lightly developed countries have little power over their futures with regard to the climate.

This brings us back for the present to Africa, where large numbers of people live on subsistence means, with agriculture vulnerable to drought or extreme rain. Their survival is marginal compared to the populations in the industrial economies, and global warming is likely to disproportionately upset their economies and lifestyles. That aspect of global warming will now be included.

Tomorrow: major climate change impacts facing all of Africa.

Be brave, and be well.

365 Days of Climate Awareness 229 – Overview of the African Climate

Much of Africa sits in the Intertropical Zone, the roughly 47° of latitude between the northern Tropic of Capricorn and the southern Tropic of Cancer. The continent is warm overall, with only a few temperate zones at higher elevations. There is greater range annually in precipitation than in temperatures, and this has more to do with the shape of the land mass and wind patterns. The northern and southern coasts have pleasant Mediterranean climates, but between them are tropical zones of both arid and rainforest type.

Köppen-Geiger climate diagram of Africa.

Annual rainfall in Africa.

The Sahara Desert (named directly from the feminine Arabic term for desert) covers 9.2 million km²/3.6 million mi² (13 times the size of Texas!), nearly 31% of the entire continent. It stretches from east to west across the entire northern portion of Africa, with only a few tiny oases and a narrow band of temperate coastline. The Sahara’s albedo is 32% and helps create the intensely stratified atmosphere which prevents vertical circulation and keeps the region virtually rain-free. Meanwhile, farther south, even as insolation increases approaching the equator, the rain forest, with an albedo as low as 9%, retains heat and moisture retention which reinforces the intensely rainy climate. Further south still, the climate becomes arid again over the bottom quarter of the continent.

Satellite image showing Africa's major climatic zones.

A glance at global wind cell circulation shows another aspect to Africa’s climate pattern. Converging, moist winds across the lower tropics tend to be loaded with moisture and produce the intense rains of that region. Farther to north and south, where the Hadley cells reach their poleward limits, dry, cool air descends back to earth, corresponding closely to the arid latitudes in the northern and southern areas of the continent. The elevations of the East Africa Mountains and the Atlas Mountains of Morocco do feature snow and 15-20 glaciers, though the glaciers are generally melting away.

Global circulation cells and Africa.

Tomorrow: introduction to climate justice.

Be brave, and be well.

The Sahara.

The Sahel.

African Savanna.

The Congo rain forest (note the terraced agriculture!)

Mt. Kilimanjaro, Tanzania.

The Atlas Mountains, Morocco.

365 Days of Climate Awareness 228 – Africa

Africa is a continent which covers 30.3 million km²/11.7 million mi², stretching across the equator from roughly 37°N to 34°S latitude, and from 52°E to 17°W longitude. 1.3 billion people, about 16% of the planet’s total population, live there. It forms the southern coast of the Mediterranean sea, approaching to within 13 km/8 mi of Spain in the Straits of Gibraltar in the west, and connecting to Arabia via the Isthmus of Suez in the east. Contrary to popular conception, the southernmost point of Africa, where the dividing line begins between Atlantic and Indian Oceans, is Cape Agulhas. The Cape of Good Hope is farther north and west.

Physical and political map of Africa.

Africa is considered by most anthropologists to be the cradle of the human race. Africa formed the heart of the ancient continent of Gondwana, which sat across the equator and was tremendously biodiverse. 140 million years have passed since Gondwana broke up but Africa has maintained its position in the tropics, and so has remained biologically abundant. Hominids appeared about 7 million years ago, and remains of Homo sapiens dating to 300,000 years ago have been found all over the continent.

Africa's position within Gondwana, 200 MYA.

Simplified bedrock map.

Geologically Africa is composed of four mineral-rich cratons, ancient igneous and metamorphic rock masses 3.5 billion years or older, within the larger continental mass. There are no subduction zones in or around the continent, making it quiet tectonically, except for the rift valley in the east which, if it continues rifting, will eventually separate the horn into a narrow continental strip somewhat like Madagascar. (The East African rift continues north through the Red Sea into the Jordan River rift valley, which includes the Dead Sea.)

East African Rift Valley. The spreading system extends up through the Red Sea and Jordan River valleys. Fun fact: the Mississippi River Valley and much of the Great Lakes basins are failed rifts!

The northern continent is dominated by the Sahara, the world’s largest desert outside of the Arctic and Antarctic (making it the world’s largest “hot” desert). South of that is the Sahel, the semiarid grassy transition from desert to savanna further south. The savanna is grassy, with more trees, and transitions into the equatorial rainforest. Continuing further south the climate becomes drier (except for the east coast) and cooler, with desertlike conditions on the southwest portion of the continent, arid south central, and savanna in the southeast.

There are 54 countries in Africa, with thousands of spoken languages. Much of the continent is not economically developed, due partly to the difficulties of geography, with the desert and rainforest, and more recently due to  of the slave-gathering and colonial practices of European countries and the United States.  It is estimated that as many as 50% of the continent’s population lives in economic poverty. Economic development has been spotty and uneven, with some countries like Nigeria and Kenya becoming more industrialized but failing to spread that prosperity to much of their populace.  Especially in areas like Nigeria, the influence of western economies exploiting the region’s oil resources remain an ongoing part of the social problems.

Tomorrow: overview of the African climate.

Be brave, and be well.

365 Days of Climate Awareness 227 – The Maldives and Sea Level Rise

The Maldives is microtidal, with a spring tide range of less than 1 m/3.2 ft. Annual sea level can vary by up to 1 m due to natural variations like the Indian Ocean Dipole. So mean sea level is a noisy signal but according to tidal gauge and satellite data has risen by nearly 50 cm in the last 35 years. IPCC models show sea level continuing to rise by another 50-100 cm by 2100, which will make the Maldives partially or totally uninhabitable.

IPCC Shared Socioeconomic Pathways (SSPs) with their predicted population and economic trends.

The Intergovernmental Panel on Climate Change  (IPCC) has published a set of Shared Socioeconomic Pathways (SSPs) which it uses as the backdrop for its various climate change model scenarios, ranging from less severe impacts to more severe. Briefly:

• SSP1: sustainability – the green road, low challenges to mitigation & adaptation
• SSP2: medium road, moderate challenges to mitigation & adaptation
• SSP3: regional rivalry - rocky road, high challenges to mitigation & adaptation
• SSP4: inequality, low challenges to mitigation, high challenges to adaptation
• SSP5: fossil-fueled development, high challenges to mitigation, low challenges to adaptation

Two scenarios, 1 and 5, lead to predicted sea level rise of 0.43 m/1.4 ft and 0.86 m/2.8 ft by 2100. The lower scenario would result in roughly 77% of the Maldives being flooded; the high scenario would inundate more than 90%. NASA estimates that by 2050—less than thirty years from now—more than 80% of the islands could be uninhabitable.

Predicted sea level rise at Malé, by 2050, for several SSPs (NASA).

Predicted future sea level rise curves for Malé (NASA), SSPs 1 & 5 (the second number refers to the scenario's associated radiative forcing: +1.9 W/m² and +8.5 W/m², respectively.

An attempt is underway to mitigate this, by raising one of the islands, Hulhumalé, an extra meter above its neighbors. As in the case of Kiribati, this is a race against time with no certain finish line. Citizens use their own improvised methods, such as building tiny breakwaters with concrete blocks, to reduce erosion.

Hulhumalé

Makeshift concrete block seawalls.

Fresh water has also become more of a problem in the era of rising seas. In 2004 only 11% of the Maldives islands had potable freshwater, but the Indian Ocean tsunami of that year contaminated the remaining aquifers. Now residents rely on collected rainwater. Water from the shallow aquifers there are is not used for eating or drinking.

Tomorrow: introduction to Africa.

Be brave, and be well.

365 Days of Climate Awareness 226 – Introduction to the Maldives

The Indian Ocean is the third largest ocean (behind the Pacific and Atlantic), covering almost 20% of the earth’s surface. It contains many thousands of islands and there is no realistic way to address them all in this series (or it would become more like the 365,000 Days of Climate Awareness). Besides, the climate issues faced by coralline islands (and volcanic islands too) worldwide are very consistent. Sea-level rise is the paramount issue for land which averages less than 2 m elevation above mean water level.

The Maldives in the Indian Ocean.

It’s estimated that there are more than 670,000 islands worldwide, including oceans, lakes and rivers. And there are, at present, 195 countries. Though I’m American and this series has clearly focused mostly on the United States, the sheer range and number of locations around the earth prohibit looking at each one. Furthermore, there is the question of resources.

Closer-up map of the Maldives island chain.

The wealthy, industrialized countries—the ones most responsible for this growing climate crisis—are the ones with the most lavish and advanced scientific study capacities. As we’ve seen in the case of a country like the Philippines, their climate monitoring systems are limited compared to those of the United States, and in fact frequently borrow from them (NOAA is a worldwide source of information, for the public, scientists and other governments alike). The often astoundingly detailed climate monitoring data available through NOAA and NASA simply don’t exist in most other parts of the planet. So to speak, the resolution of our image is not uniform around the globe. Given the limitations of this space, and the limitations of available information, we’ll continue our somewhat orderly hopscotch looking at climate realities around the planet.

Malé, the Maldives' capital.

The Maldives are an archipelagic nation roughly 750 km/470 mi southwest of India, consisting of 1,190 islands grouped into 26 atolls atop the Chagos-Laccadive Ridge southwest of the Indian mainland. It is the smallest nation in Asia, the islands covering 298 km²/115 mi²,  and it extends from almost 7°N to 1°S latitude, at 73° east longitude. As much as 10,000 years ago coral reefs began growing on the shallowest parts, resulting in the Maldives chain. The islands average 1.5 m above sea level, with a maximum height of 5.1 m, making it the lowest-lying country on earth, and therefore especially vulnerable to sea-level rise.  

A few islands in the Maldives chain.

The Maldives has a population of roughly 560,000, nearly all native Maldivians. There is quite a range in theorized dates when the islands were first settled, from 3300 to 500 BCE. Early artifacts show influence from India. Culturally society was Buddhist for much of its existence, until Muslim traders in the 11^th century effected its transition to Islam. In the 1500’s the Portuguese attempted to colonize and Christianize the islands, but were driven out. The Dutch later assumed power but largely left the Maldives alone, until they were replaced in Ceylon by the British in 1796. After a politically turbulent 20^th century, in 1968 the Republic of Maldives declared its independence.

Tomorrow: sea level rise and the Maldives

Be brave, and be well.

365 Days of Climate Awareness 225 – Impacts on Philippine Agriculture

The Philippines sit entirely in the tropics, and the northwest Pacific is one of the most active areas in the world for cyclones. Furthermore, the impacts of ENSO are large across the Philippine islands: La Niña tends to bring rain, and El Niño to bring drier weather. These effects have been tracked in recent years, along with fundamental variables like air and sea temperature. The resulting picture is complex.

Air and sea surface temperature trends are unambiguous, showing increases throughout the 20^th and early 21^st centuries. One of the fundamental components of climate change analysis, including the concept of “global weirding”, is that increases in heat content in atmosphere and ocean, by adding energy to the climate system, should result in more frequent and energetic storms and rainfall. And while this is to some extent true around the world, in reality the global climate response is not a simple linear increase. That is the case in the northern Pacific as well.

NOAA's ONI (Ocean Niño Index), 1951-2022.

NOAA’s Ocean Niño index (ONI)  has come to help define El Niño vs. La Niña years. It is a measure of sea surface temperature differences across the tropical Pacific, and it shows no major trend over the past seventy years, either in frequency, mean (trending toward one state or another), or amplitude (severity). The most severe El Niño years (dry for the Philippines, elevated N hemisphere temperatures) seem to be becoming a bit more so, and perhaps La Niña years (wet for the Philippines, warm water is driven by wind deeper into the ocean) are becoming more frequent.

But there is no obvious trend in cyclone count or severity in recent decades. (And let’s be clear: this is not disappointing. We’re not rooting for destruction!) But as the ocean continues to absorb more heat, any increase in La Niña activity can reflect an increase in system storage of heat, even if it is not expressed immediately through major storms. But factors can combine. Even if storm activity is not by itself notably increasing, along with sea level rise they are producing increasingly damaging floods.

Rice yields (gray), by quarter, by temperature ranges for present-day and modeled future climates.

Severe droughts tend to coincide with El Niño years, which begin to have an impact around the end of the year, during the rainy growing season for rice. During the first quarter (January-March), when the rice fields are most productive, heat has the least effect, though drought the most, on productivity.   

Tomorrow: introduction to the Maldives.

Be brave, and be well.

365 Days of Climate Awareness 224 – The Philippines and Climate Change

Only after industrializing following World War II and gaining its independence, has the Philippines (the islands are plural, the country is singular) begun emitting any measurable amount of carbon dioxide or other greenhouse gases. Since then the country’s rise in greenhouse gas emissions has been steep, reaching 140 million tons by 2020. This represents about 0.4% of the world’s total emissions, for a country with 1.4% of its population.

Philippines annual carbon dioxide emissions.

Per capita carbon dioxide emissions.

Only two brief downturns in emissions interrupt the very nearly exponential growth of the Philippines’ increase in CO₂ emissions.  This is a tiny portion of the whole, but represents the ramp-up from pre-industrial to industrial economy, relying on fossil fuel and emissions. The Philippines are one of the many countries around the world industrializing late, in an era when climate change science has come of age and is already prescribing emissions limits.

Carbon dioxide emissions by fuel.

World fuel consumption by type.

In a world which still depends mostly on fossil fuels, this is effectively a limit on economic activity. And that is the fundamental pressure which keeps our global society on its unsustainable path. Temperature trends in the Philippines’ air and sea are clear, though hardly the result of the country’s economic growth. The lot of the Philippines, like many smaller, less wealthy countries around the planet, is in the realm of climate justice, of balancing human rights against economic and political convenience. (We will return to the topic of climate justice down the road a bit—it’s worth a significant section of its own, after our world tour.)

Air temperature anomalies, 1951-2009.

Sea surface temperature anomalies, 1850-2010.

Tomorrow: climate change, ENSO and Philippine agriculture.

Be brave, and be well.