DThe sharp increase in the rate of melting ice in Greenland and East Antarctica is, along with the heat wave that grips Australia, among the latest manifestations of the changes that our planet is experiencing and its atmosphere. Concerns surrounding the risk of melting ice causing rising sea levels were previously focused primarily on large glaciers. But scientists have found that the biggest loss recently from the vast Greenland ice sheet, which is two miles thick, occurs in the southwest of the island which is mostly glacier-free. Combined with a recent analysis to restore Antarctic glaciers that were previously considered stable, this new study made a terrible reading. This is because of what was told to us about the possibility of sea level rise, and sea warming associated with coral death and chaotic weather, but also because it highlights the difficulty of fully understanding the climate system.
Last year the UN Intergovernmental Panel on Climate Change urged the government to work towards the most ambitious targets in the 2015 Paris agreement, and global temperature increases not more than 1.5C. Many experts worry that factors including Donald Trump's election in the US and Jair Bolsonaro in Brazil mean that even a simpler goal of sticking to current commitments, putting the world on track for a 3C increase, remains a big challenge. At present, global carbon emissions are still increasing. But if people all over the world are accustomed to the idea that higher temperatures and the increased frequency of extreme weather events are normal new – recent polls in the US show 72% of Americans believe that global warming is important, the highest number ever – we are arguably less advanced in our understanding of ocean warming.
Sea levels rise so scientists hope to accompany a 3C rise in temperatures that will soak cities including Shanghai, Osaka and Miami along with parts of Rio de Janeiro and Alexandria – less than a century from now. Among countries, Bangladesh will be greatly affected, with one estimate showing that 250,000 people have been forced to move each year, making them environmental refugees. The facts on the ground, as well as predictions, are the reasons why climate activists have long linked their goals to broader concerns about social justice. Just as carbon emissions must be limited to protect the livelihoods of people who have struggled in areas prone to drought and desertification, sea level rise must be limited to protect millions of people living on the coast and in low-lying areas. The movement of people throughout the world, including but not limited to refugees, is in some cases a direct consequence of environmental change.
Weather and climate systems are very complex, and sea level is difficult to predict with confidence. Ice sheets and glaciers have surprised scientists by behaving in unexpected ways. But while trying to limit emissions in the future remains the most urgent task, these unpleasant findings highlight the need to overcome the carbon consequences that have been emitted. Sea level rise will continue long after emissions peak. We must adapt to changes in the shape of our world.