Can we predict what global warming will be like when looking at the past?
Several studies have tried to assess the consequences of global warming by examining fossil records. From these, paleontologists aim to correlate the Earth's temperature with the occurrence of plant and animal species. It appeared that prehistoric climate changes have had a dramatic impact on plant and animal life. Climate changes induced migration of animals to new habitats where conditions were similar to those prior to the climate changes. This behavior is anchored in the genes and is less demanding than adapting to the new conditions. When animals cannot adapt or find favorable conditions elsewhere, they may not be able to survive, and the species may become extinct. This happened with most of the amphibians, some 300 million years ago, when the climate became much more arid than it was before. However, some other species might benefit from climate changes, such as the early tetrapods that took over the reign by amphibians in this period, which eventually led to the expansion of reptiles, birds and mammals and ultimately humans.
What consequences does global warming have on life today?
Polar bears have become emblematic of today's climate changes, and not without reason. These animals have a much higher metabolic rate than had been assumed before and need to eat one adult seal or 19 newborn seals every 10 to 12 days. Now that the sea ice is melting away under their feet, they lose their possibilities to hunt. They are wandering around to find good hunting grounds, and thus spend more energy walking and capture less prey. This makes polar bears extremely vulnerable to global warming.
On average, birds and mammals may be better off in adapting to climate changes than amphibians and reptiles, as they can regulate their own body temperature. This may change biodiversity, as occurred during prehistoric climate changes. Also, the body size of birds may be decreasing with higher temperatures, but the effects of this surprising finding on birds' health are not known at present.
Effects of rising temperatures are also noticeable underwater, in the oceans. Coral bleaching has been in the news quite regularly lately. It is a stress response of coral to elevated temperatures and leads to massive coral mortality. While bleaching has been a rare phenomenon in recent history, it is now happening frequently. So frequently that coral does not have enough time to be replaced for survival.
Other effects of global warming that have been reported lately are the intensification of hurricanes and accelerated temperature rises in big cities. Both took a heavy toll as many people lost their lives in the storms and heat waves.
Can we predict the consequences of global warming for the future?
Scientists take historic and current measurement data and feed them into computational models that predict how temperatures will change over time. These models are constantly being adapted to incorporate new scientific findings. For example, scientists have discovered a potential new source of carbon emission in ponds in the melting High Arctic, which might accelerate global warming even further. Another study found that polar waters warm up much more than what scientists believed. This has not been yet built into current models of global warming.
There is currently much debate over methods and measures that can be adopted to slow down or even halt global warming. The Paris Climate Agreement in 2015, and the United States withdrawal from it, have dominated climate news. One of the measures that has been advocated as a potential way to reduce carbon emissions is removal of the hundreds of billions of dollars subsidies on fossil fuels. However, scientists found that this will have only minor effects on emission, so that other measures will have to be formulated and evaluated. In the meantime, researchers look for ways to utilise greenhouse gases in a meaningful way, instead of letting them escape into the atmosphere.
One study reported on the conversion of methane into useful chemicals that can be used in the production of plastics, agrochemicals and pharmaceuticals. Also, Mother Nature herself may give a helping hand in that the sun is likely to emit less radiation by Mid-Century. Although this will induce a cooler period and slow down global warming to some extent, this is clearly not enough to halt human-induced global warming. Science and politics will have to join to come up with accurate models as well as efficient strategies to limit the current rise in global temperatures.
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