Gavin Schmidt of REAL CLIMATE continues to follow a disturbing warming trend in 2017. He predicts 2017, which is now drawing to close, will be either the second or third warmest on record, behind the leader 2016. Also, it will be the warmest ever for a year not under the influence of El Nino. Schmidt has a very informative site
that provides a commentary on climate science by working scientists for the concerned public and working journalists. REAL CLIMATE aims to provide a quick response to developing stories and provide the context sometimes missing in mainstream commentary. I like to go to Schmidt’s archives, such as July, when RealClimate posts this:
Probably everyone has heard this argument, presented as objection against the findings of climate scientists on global warming: “The climate has always changed!” And it is true: climate has changed even before humans began to burn fossil fuels. So what can we conclude from that?
Here is a quick quiz. Do you conclude…
(1) that humans cannot change the climate?
(2) that we do not know whether humans are to blame for global warming?
(3) that global warming will not have any severe consequences?
(4) that we cannot stop global warming?
I like the answers posted for each of these four questions, but especially for #2. Give it a read:
(2) Imagine there has been a forest fire. The police have extensive evidence that it was arson. They know the place where the fire began. They found traces of fire accelerants. Witnesses observed a man whose car was parked nearby. In his trunk the police finds bottles with fire accelerants, and in his house they find even more of it. He has been convicted for arson several times before. Plus some further evidence. In court, he defends himself: forest fires have always occurred lit by lightning, even before there was any man on Earth. Therefore he must be innocent. Does the argument convince you?
The evidence for the human cause of global warming is overwhelming. This is why there has been a consensus among climate researchers for a long time, and almost every scientific academy on the planet has come to the same conclusion. The most important evidence: when it gets warmer, the energy has to come from somewhere (1st law of thermodynamics). It can only come through the radiation budget of our planet. (No, Rick Perry, the energy does not come out of the ocean. To the contrary, measurements show heat is going into the oceans). The changes in this energy balance are quite well known and are shown near the front of any IPCC report. – The biggest factor is the increase in CO2 concentration as well as a few other greenhouse gases, also added by human activities. The incoming solar radiation has changed just a tiny bit in comparison – since 1950, by the way, it has even decreased and thus offset a small part of the human-caused warming – hence humans have probably caused more warming than is observed (best estimate is 110% of observed warming).