365 Days of Climate Awareness 329 - AR6 Vol 2, Chap 2: Terrestrial and freshwater ecosystems

When researchers look not only globally, but in much greater, zoomed-in detail on ecosystems around the world, the impacts of global warming are visible and increasing. Longer and more intense warm seasons, shorter and warmer cold seasons, increasingly violent and erratic rain and snowfall in wetter areas, and even hotter, drier arid zones are changing patterns of life across the planet.

IPCC Assessment Report 6, Vol 2, Chap 2. Global land use changes, past and predicted.

Not only are ocean temperatures rising, but lakes, ponds and rivers are growing warmer too. This is leading to higher primary production—algae and plants—in the water. This leads to browning—higher rates of organic decay, which in turn lowers oxygen levels. Ice cover over freshwater bodies has decreased by 25% in the last decade. Fish and other aquatic species lack the freedom to migrate further toward the poles that terrestrial and aerial species have, so this is leading to declines in animal populations and water quality in freshwater ecosystems around the world.

IPCC Assessment Report 6, Vol 2, Chap 2. Lake and river temperature changes.

Increasing temperatures are also leading to higher disease rates in plants and animals. With a high level of confidence, the severity, frequency and number of novel vectors are all increasing.  Diseases borne by ticks, helminth worms and fungi are emerging in new regions around the globe, including the Arctic and high elevations in Nepal.

IPCC Assessment Report 6, Vol 2, Chap 2. Northern hemisphere ice cover changes.

The heat is contributing to a rising tide of extinctions around the world, as heat waves cripple local populations. The extinctions have been especially common in tropical areas, freshwater ecosystems, and among animals. Several species have been documented with high confidence to have gone extinct due to temperature and sea level rise, including the golden toad of Costa Rica, and two inhabitants of Australia’s Great Barrier Reef, the lemuroid ringtail possum and the Bramble Cays melomys (a species of rat).

IPCC Assessment Report 6, Vol 2, Chap 2. Increasingly severe impacts of climate events.

Ecozones are shifting toward the poles (so far an average of 20 km since 2015), with plants seeding further away from the equator and animals migrating which can. With the trend to hotter seasons has also come increasing frequency and severity of wildfires, with recently observed trends bearing out earlier model predictions. While larger and more intense fires in western North America have been confidently linked to global warming, in other continents like Australia and South America, the confidence level is lower (due to less data). Trees are dying from the heat, with total forestation loss of more than 20% since 1945. Forests are a vital global carbon sink. Their shrinkage and loss only increases the rate of CO₂ gain in the atmosphere.

Tomorrow: AR6 Vol 2, Chap 3: Oceans and Coastal Ecosystems.

Be brave, be steadfast, and be well.