So humans are causing it...
The recent release of the IPCC report was much anticipated by scientists, politicians, economists, etc. There are several very important additions and changes when compared to the 2001 report. The one that has garnered the most media and public attention, and rightfully so, is the statement that the panel is 90% certain that human-based greenhouse gas emissions are the cause of recent global warming. This is simply confirmation of what most scientists have suspected for quite some time. In this posting I'd like to make two points related to this.
First, take a moment to review my earlier posting on the mechanisms that control climate change. These include factors such as the energy output of the Sun, ocean and continental configurations, volcanism, and so on. The biggie, as I put it, are greenhouse gases. The reason for my emphasis being the fact that this is the only one of the mechanisms that is changing on a timescale similar to the climate change that we are currently observing. And the rate of change in greenhouse gas concentrations has been significant since the start of the Industrial Revolution in the mid-nineteenth century, and it continues to accelerate. So, even if there are other mechanisms at work, say some slow changing of Earth's orbital axis, greenhouse gas concentrations remain the source of most immediate concern. And, there is every indication that our rapidly growing consumption of fossil fuels, most notably petroleum and coal, are fuelling (pun intended!) the acceleration.
Now here's my second point. Ask yourself a question, supposing that human greenhouse gas emissions are not the only things at work, right now, that are warming the planet. Say that there is something going on with Earth's tilt, or perhaps the Sun is going through a mid-life crisis and is increasing its energy output. Maybe there are feedbacks that are increasing natural greenhouse gas emissions (as has happened in the geological past). Well, we certainly have a handful of problems then, don't we! So no matter what, the fact is that the Earth is warming, and that warming is beginning to cause problems for humans and the rest of the natural world. The consequences are unpleasant, and for our sake, for our childrens' futures, and for the rest of life on the planet, something must be done about it. Well, we could attempt to "correct" Earth's tilt, or we could attempt to cool down the Sun, or we could address greenhouse gas concentrations. Seems to me that the latter is the only mechanism over which we have any influence at all!So here's my message to all of you, regardless of your stance on the benefits of curbing emissions, the potential damage to economies, the injustice of asking all countries to contribute to the solution: We have no choice. The planet is warming. Some, most, maybe all of the warming is being driven by increasing greenhouse gas concentrations. Regardless of the relative contributions of other sources of greenhouse gases, we have control over one source only. ourselves. So we need to get over it and MOVE ON!
Maybe in my next posting I'll discuss some of the approaches that are being discussed, including alternative sources of energy, energy conservation, and carbon sequestration.