The fifth report from the Intergovernmental Panel on Climate Change (IPCC) was released late September of 2013. To no one's surprise, except perhaps the climate negaters still out there (and even they aren't surprised—just nonbelieving), the report is more of the same. More of the same findings that were reported in the first four IPCC reports. More findings that the earth's climate is warmer, more evidence that sea levels are rising, snow and ice levels are shrinking, more greenhouse gases are increasing. The same results they warned about in the first four reports—only more so. Much more.
Each report the IPCC comes out with is more dire than the last. In the Fifth Assessment Report of the Intergovernmental Panel on Climate Change: Summary for Policymakers, the authors state: “Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia.”
IPCC authors emphasize every statement and projection with a rating system: “low, medium and high confidence” to “likely”, “very likely” to “virtually certain.” Deniers may seem to take this as a way for the scientists to hedge their bets, and use language that equivocates. However, when a scientist says something is “virtually certain”, one should take that a whole lot more seriously than, say, if a politician were to say he or she is “virtually certain” that they will keep their campaign promises. Beneath the scientists' hesitant sounding language is pretty alarming stuff. They also use words like unequivocal and unprecedented. .
Here are the latest findings, and how projections have changed from earlier reports :
Assessment of human contributions to warmer or more frequent hot days: from Likely to Very Likely
Increased frequency and duration of Heat Waves: from Likely to Medium confidence in many (but not all regions) to Medium confidence on a global scale; Likely in large parts of Europe, Asia, and Australia. The assessment of human contribution to this change moved from More Likely than not to Likely.
Increased frequency and intensity of Precipitation events: Changed from Likely over most land areas to Likely more land areas with increases than decreases. Their projection changed from Very likely over most land areas to Very likely over most of the mid-latitude land masses and wet tropical regions.
Increased intensity/duration of droughts: Changed from Likely in many regions, since 1970 to Medium confidence in some regions to Likely changes in some regions, with a low confidence on a global scale.
Increase in intense tropical cyclones: Changed from likely in some regions to low confidence in long term changes to virtually certain in North Atlantic since 1970. Projections for the next century changed from Likely to Medium Confidence in some regions to Likely (medium confidence) on a regional to global scale.
Increased incidence/magnitude of extreme high sea level: Projections have changed from Likely to Very Likely.
The contrasts between wet and dry regions will increase. Dry areas will become dryer, and wet regions will grow wetter. Monsoon precipitation will likely increase, even as monsoon winds lessen. And the monsoon season will likely be lengthened in many regions.
The disappearing ice sheets in Greenland and Antarctic continue to be of cause for concern; the rate of loss was unprecedented: the amount of sea ice has decreased every decade since 1979, and sea surface temperatures were higher than in the last 1450 years.
Another impact we can expect to see is rising ocean temperatures. As much as 90% of the energy increase over the last 40 years is stored in the ocean. In addition, the ocean is absorbing about 30% of man-made CO2 emissions, resulting in ocean acidification.
Meanwhile, sea levels are rising: 3.2 mm a year in the last 20 years, most of it due to glacier loss and ocean thermal expansion. About 70% of coastlines will experience sea level change.
Melting permafrost and rising sea levels are measurable and quantifiable, and these changes are no longer projections, but things we are seeing happening right now: temperatures are rising, extreme weather events are occurring more freqeuently. But s far as climate change negaters are concerned, where the IPCC starts getting controversial is when it starts talking about the causes of these changes. The IPCC clearly states that “atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years.” This increase in greenhouse gases are unprecedented in the last 22,000 years: and that it is extremely likely that human influence is the cause.
So for the fifth straight report in a row, the IPCC is warning us that dire things are happening to this planet, and that we are causing it. The fifth report offers nothing we haven't heard already. But we never really paid attention the first four times: how many times does the IPCC have to cry wolf before lawmakers, policymakers, industry, and society finally take them seriously?
IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S. K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.