The Intergovernmental Panel on Climate Change (IPCC) released its fifth report on Friday. Nothing much has changed since the last report. The biggest difference that I can see is the amount of certainty around some of the conclusions. Since this is science and happens in the real world, unanimity on everything is not possible. But there is unanimity, among the 800 scientists who helped prepare the report, on the following:
1. “Warming of the climate system is unequivocal...The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased.”1
There is unanimous agreement, therefore, that the world has warmed. This has nothing to do with the past, before we had ways to measure such things, or the future, which must rely on predictions that may be disputed.
Another way of expressing this statement is that global warming is real and it is happening right now.
2. “Each of the last three decades has been successively warmer at the Earth's surface [in the atmosphere] than any preceding decade since 1850.”2
This statement indicates that we are on the forefront of this problem and it shows no signs of reversing. There is unanimity among climate scientists on this point.
Many climate skeptics point to isolated incidents of cooling, such as an increase in Arctic Sea Ice or a particularly cool year, to challenge global warming. Note, however, that scientists do not claim that every year will be the warmest ever, or that sea ice will decrease every year. These kinds of data are best collected over a period of decades, not years. It would also help if observers take into account cyclic phenomena, such as the el Nino current, or volcanic eruptions. A simple glance at a falling thermometer will not make any difference to the overall trends.
As a result of this increased warmth generally, there are also specific results. Not everyone agrees on these events, but the IPCC considers them likely or very likely. The number of cold days and cold nights have decreased and the number of warm days and warm nights has increased on the global scale. The frequency of heat waves has increased in Europe, Asia, and Australia. There are more land regions where the number of heavy precipitation events has increased than where it has decreased. This includes North America and Europe.
3. “Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010.”
Humans live on land and are thus confronted daily with atmospheric weather. We do not often consider that the oceans contain much more substance than the atmosphere above us, and that therefore the oceans have absorbed far more energy from excess CO2 than the air. This is a lucky thing, since without the ocean's ability to absorb CO2, we would be in far worse shape than we are.
4. “Human influence has been detected in warming of the atmosphere and the ocean, in changes in some climate extremes.”3
Evidence for human influence has increased in the last 5 years.
5. “Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.”4
Up to this point in the summary, IPCC has only considered what has happened in the past and what is happening now. Predictions for the future are much less definite. Some of the computer models are better than others. IPCC predicts weather for land masses better than for local areas. Predictions of melting icecaps are particularly elusive, resulting in huge variations of outcome. For instance, the melting of the Greenland Icecap would contribute 15 to 30 feet to ocean levels, but we cannot as yet predict when that will occur.
What we know is that longer rainy seasons and shorter growing seasons will not bring us more crops. Longer droughts will require better planning and inventions to save energy and maintain our standard of living.
One of the new features of this version of the IPCC report is the addition of scenarios that could alleviate the worst effects of global warming. These scenarios will be of vital importance in the years ahead.
We can hope that we do not follow the lead of Australia, which has just abandoned all its governmental planning for global warming. There seems to be a strong Luddite wind blowing in the world right now. People fear the future and don't trust Science to help them find a way forward. The question to ask ourselves is this, if we don't trust Science, who can we trust? The Bible and the Qur’an will no doubt give us solace as quality of life erodes on our planet. Only Science can offer us a way to fight that erosion.
We need leaders who will tell the truth and make plans for the future. Let us hope we will find them.
1Working Group I Contribution to the IPCC Fifth Assessment Report Climate Change 2013: The Physical Science Basis
Summary for Policymakers 2, IPCC, 2013, http://www.climatechange2013.org/images/uploads/WGIAR5-SPM_Approved27Sep2013.pdf.