How does all this affect what we know about global warming?
The climate is warming. Nothing revealed by Climate-gate changes that fact.
For example, satellite data from two different scientific groups, the University of Alabama at Huntsville and Remote Sensing Systems, indicate that during the last 30 years average global temperatures have been increasing at a rate of 0.13 degree Celsius and 0.153 degree Celsius per decade, respectively. The disputed CRU surface data indicate an increase of 0.15 degree Celsius per decade since the mid-1970s, which is within that range.
In addition, research has uncovered numerous trends that are consistent with a warming world. For example, sea levels are rising, mountain glaciers across the globe are receding, the behavior of plants and animals indicates that spring is coming earlier, recent satellite monitoring finds that ice sheets in Greenland and Antarctica are thinning, and during the last 30 years the area covered by Arctic sea ice has been declining by 4 percent per decade.
If the planet is definitely warming, why have temperatures remained more or less steady since 1998?
Although the 2000s are the warmest decade in the modern record, there has been little discernible warming since 1998. Why this has happened and what it means are matters of dispute. Researchers convinced of global climate change believe the pause is the result of natural variations, such as periodic shifts in ocean currents, that will dissipate during the next few years, followed by a resumption of warming, perhaps even at a faster pace. Skeptics argue that the computer models’ failure to predict this pause suggests they cannot reliably predict future warming.
What changes will occur as a result of Climategate?
One happy result of Climategate could be that the climate research community heeds Georgia Tech climatologist Judith Curry: “Climate data needs to be publicly available and well documented. This includes metadata that explains how the data were treated and manipulated, what assumptions were made in assembling the data sets, and what data was omitted and why.”
Greater transparency should not be limited to temperature data but should include all aspects of climate science, including the software used by computer climate models. Only through such transparency can other researchers determine whether the models are adequate forecasters of future climate change or merely prejudices made plausible.
But there is one important thing that more transparency won’t fix: the complications and uncertainties inherent in crafting policies to reduce global warming.
Making climate data and climate model code available to independent researchers will lead to a deeper understanding of the scientific uncertainties surrounding man-made global warming, but this could render projections of future warming less clear, demonstrating that it is harder than previously believed to know what the best policies are to address the problem.