There is plenty of room for argument about the rate at which the world is warming, the degree to which humans are culpable, the likely outcomes and the most effective steps to be taken. But there is not much argument about the big picture. The climate researchers at East Anglia were early in the field, but they were not alone. Their conclusions have been backed by scientists at the Met Office, from other British universities, and from the British Antarctic Survey; by oceanographers from Germany, California and Massachusetts; by planetary scientists from Nasa and the European Space Agency; by naturalists in a Europe-wide network of botanical gardens; and by climate historians, foresters, zoologists, palaeontologists, glaciologists and geographers on six continents. Scientists from the US National Oceanic and Atmospheric Administration have repeatedly released findings that broadly confirm the same big picture, and for eight of the past nine years those researchers were funded by a Republican administration that would have much preferred to hear a different story. In 2001, the national science academies of 17 nations – including Britain’s Royal Society – urged governments to avert future calamity by agreeing to limit greenhouse gas emissions; within three weeks, the US National Academy of Sciences had joined the chorus, and begun to sing from the same hymnal. Although any single piece of evidence is open to reinterpretation, the mass of data assembled all seems to point in one direction: towards a warmer and increasingly uncomfortable world.
Global average temperatures have gone on rising. Nine of the 10 warmest years ever recorded have occurred in the past decade. In the past three decades, glaciers have receded at alarming rates in Alpine Europe, tropical Africa and sub-Arctic Alaska. The Greenland icecap has begun to melt and the north polar sea ice has become both smaller and thinner. The northern hemisphere growing season has been extended by 11 days. For reasons connected with human pressure, but also possibly with global warming, arid regions have become more arid, floods more catastrophic, hurricanes and cyclones more destructive. Millions of very poor people have been forced to abandon their homes, to kill their cattle, to walk away from their farms. Oceans have become more acidic, and coral reefs have been bleached. Forests have burned; rivers in the drier regions have slowed to a trickle, or dried up altogether.
Some events may be considered as consequences of natural variation in a climate cycle, but the intensity and frequency of such extreme events is expected to grow as the world warms. The lesson to be drawn from the latest round of questions about climate science is not that scientists make mistakes, and could get the future wrong. It is that we still don’t know enough about our own planet, and should be spending more on research, instead of cutting science budgets. Knowledge is expensive, but wilful ignorance could cost immeasurably more.