Dat de aarde opwarmt door menselijk toedoen (de uitstoot van broeikasgassen zoals CO2 en methaan) staat onderhand wel vast. Mensen, dieren en planten worden daardoor steeds meer in hun voortbestaan bedreigd.

Deze week verscheen er opnieuw een lijvig, 840 pagina’s tellend rapport, dit keer niet van het IPCC, maar onder auspiciën van de Amerikaanse regering. Driehonderd klimaatwetenschappers van naam en faam werkten eraan mee, waaronder een aantal leden van de prestigieuze National Academy of Sciences (NAS). Het rapport focust op gevolgen van de klimaatverandering voor de VS, en de conclusies liegen er niet om: de hittegolven, bosbranden, overstromingen en andere extreme weersomstandigheden die de VS nu al decennialang teisteren, zijn door de mens veroorzaakt.

“Climate change is already affecting the American people in far-reaching ways. Certain types of extreme weather events with links to climate change have become more frequent and/or intense, including prolonged periods of heat, heavy downpours, and, in some regions, floods and droughts. In addition, warming is causing sea level to rise and glaciers and Arctic sea ice to melt, and oceans are becoming more acidic as they absorb carbon dioxide. These and other aspects of climate change are disrupting people’s lives and damaging some sectors of our economy.

(…)

Evidence for climate change abounds, from the top of the atmosphere to the depths of the oceans. Scientists and engineers from around the world have meticulously collected this evidence, using satellites and networks of weather balloons, thermometers, buoys, and other observing systems. Evidence of climate change is also visible in the observed and measured changes in location and behavior of species and functioning of ecosystems. Taken together, this evidence tells an unambiguous story: the planet is warming, and over the last half century, this warming has been driven primarily by human activity.

Multiple lines of independent evidence confirm that human activities are the primary cause of the global warming of the past 50 years. The burning of coal, oil, and gas, and clearing of forests have increased the concentration of carbon dioxide in the atmosphere by more than 40% since the Industrial Revolution, and it has been known for almost two centuries that this carbon dioxide traps heat. Methane and nitrous oxide emissions from agriculture and other human activities add to the atmospheric burden of heat-trapping gases. Data show that natural factors like the sun and volcanoes cannot have caused the warming observed over the past 50 years. Sensors on satellites have measured the sun’s output with great accuracy and found no overall increase during the past half century. Large volcanic eruptions during this period, such as Mount Pinatubo in 1991, have exerted a short-term cooling influence. In fact, if not for human activities, global climate would actually have cooled slightly over the past 50 years. The pattern of temperature change through the layers of the atmosphere, with warming near the surface and cooling higher up in the stratosphere, further confirms that it is the buildup of heat-trapping gases (also known as “greenhouse gases”) that has caused most of the Earth’s warming over the past half century.”

Tot zover de samenvatting.

Een zoveelste waarschuwing.

Welnu: of we nog op tijd zijn om de gevolgen van de klimaatverandering enigszins binnen de perken te houden, of met z’n allen onherroepelijk naar de ratsmodee gaan, zoals klimaatwetenschappers als Clive Hamilton (Requiem for a Species) menen, weet ik niet. Maar een ding weet ik wel: de kop in het zand steken en de realiteit blijven ontkennen, omdat ze ons toevallig niet zint en we lekker onbeperkt en onbezorgd energie willen blijven verspillen, nee, dat helpt in geen geval.