As the Intergovernmental Panel on Climate Change (IPCC) finalizes its latest climate-assessment report, a News Feature in Nature explains that since the panel’s last report in 2007, researchers have greatly improved their understanding of the factors that contribute to rising sea levels. The article is part of a special issue of Nature, examining how the IPCC and climate science have evolved over the past 25 years.
One of the most controversial elements of the last IPCC report concerned sea-level rise, and whether the panel had underestimated how much water levels will increase by the end of the century. Scientists have made enough progress since then to revise their projections, and have raised the upper estimates for how much sea levels will rise by 2100, the News Feature explains. However, oceans will not rise evenly around the globe: in some areas, including in parts of Alaska, sea levels will actually fall in the short term because the land there is slowly rising in a delayed response to the end of the last ice age. Meanwhile, along the east coast of the United States, the land is sinking and sea levels are rising faster than the global average.
An accompanying graphic spread illustrates how the IPCC has grown more confident that human activity is warming the planet, but researchers have failed to reduce the main uncertainty about how much warming will occur. The issue also includes a profile of German economist Ottmar Edenhofer, who is leading the IPCC working group that next April will release their report on ways to mitigate climate change.
With the failure in recent years of international attempts to deliver a binding treaty on emissions reductions, individual countries are finding their own ways to address the issue. This patchwork approach could work for climate-change mitigation, says climate-policy analyst Elliot Diringer in a Comment piece, but we need an overarching framework of rules by which progress can be measured. “Much of the real work to stave off climate catastrophe must happen at home,” argues Diringer. There are encouraging signs for reaching a new international agreement, he writes, but nations are still struggling with how to build ambition into the model, to ensure that collective action does reduce global emissions overall.
Also in the Comment section, energy analyst K. John Holmes explores how the first large-scale environmental assessments in the United States informed policy debates in the nineteenth century, and the parallels that can be drawn with the climate debate today.
Article appearing courtesy Celsias.