The recent “pause” in global warming and Typhoon Haiyan

It can be pretty difficult to get to grips with climate science. The climate is big and confusing, there are lots of unknown variables, and predicting the future will always be a tricky business. There are some very understandable misunderstandings but also some less forgivable basic errors that get routinely published. Let’s look at the two most common.

The IPCC Predictions

Much has been made in the past few days about climate change has supposedly ‘stalled’. For the record , it didn’t get colder. The planet is still a good 0.8° C warmer than it would have been without human activities. NASA calculated that and the last time I looked they weren’t funded by the fossil fuel lobby or the secret international consortium of wind farm enthusiasts. (wait a minute…) [1]. The reason warming has stalled in the last 15 years is because 1998 was an unusually warm year, much warmer than the years before or after it. So of course if you measure the temperature in the last 15 years you don’t see an increase from the base year of 1998. Actually, there are many individual years in the past 100 that you could pick to make the same point, but it doesn’t change the long term trend. skepticalscience.com makes this point extremely clear with the following two graphs.

warming combo

http://skepticalscience.com/cherrypicking-guide.html

There are also articles claiming that the IPCC predictions were completely inaccurate, and that the current temperatures are much lower than predicted. This is quite wrong. The IPCC gives a range of predictions based on different scenarios. Since 1990 global surface temperatures have warmed at a rate of around 0.15°C per decade which is within the range of IPCC model projections from 0.10 to 0.35°C per decade. There is also a “multi-model mean” which average together all of the different model simulations. What many newspapers did in the past couple of weeks was only show the model averages, such as Der Spiegel here.

However, it’s unlikely that the climate will follow the average, especially in the short-term.  As Dana Nuccitelli explains on Skeptical Science, “If natural factors act to amplify human-caused global surface warming, as they did in the 1990s, the climate is likely to warm faster than the model average in the short-term. If natural factors act to dampen global surface warming, as they have in the 2000s, the climate is likely to warm more slowly than the model average.” If you average the models together, then the random natural variability in the individual models is cancelled out. But the climate only behaves like a single model simulation, not an average of many. [2]

The natural factors that are currently slowing surface warming include the oceans, which go through regular natural cycles of heat exchange with the surface. Right now, measurements show that the oceans are absorbing more heat. When this cycle changes, surface temperatures are going to get a lot hotter, as they did in 1998, which was one of the largest El Ninos on record.  Thus, nothing we’ve witnessed is unexpected, at least not if you were reading the IPCC reports.

Now could this extra heat that is being absorbed by the oceans also drive more powerful storms, more frequent storms or both? Haiyan has sparked a fierce debate in the scientific community about tropical storms and our warming world. As I read in an article on Slate, a 2008 article argued that all things being equal, warmer water will make more powerful cyclones.[3] However, the warming climate can change any number of variables that will then affect each other in ways that we have not yet been able to account for. Some will contribute to more powerful cyclones and some weaker. For now there is no consensus that climate change will lead to more powerful storms: more evidence is needed. Let’s hope that it’s not the case for the sake of the people living in cyclone regions. I wouldn’t bet on it though. In 20 years time with more plentiful and accurate data it’s likely that a strong causal link between climate change and powerful storms will be established. That excess energy in the oceans has to go somewhere….

Major Fallacy: Human C02 Emissions Don’t Cause Warming

Another common mistake that I read on the internet is that we produce so little C02 that it cannot possibly contribute to the warming of the planet, so the warming must come from natural factors. It’s true that humanity produces a tiny percentage of all C02 in the atmosphere. However, the C02 naturally produced is also naturally absorbed. For example and for the sake of simplicity, the C02 produced by forests is absorbed by the oceans. So nature produces many gigatonnes of C02 but also absorbs this. This left us with an amount of C02 in the atmosphere equivalent to around 280 parts per million (ppm). What we’ve done is add to that, and natural forces haven’t been able to absorb all of what we’ve added. So now we have 400ppm. Thus, we are trapping more heat, as observed by the recorded global temperature increases. It’s like compound interest, it starts off small, but that little percent builds up over time. If you’re a student from the UK you’ll probably know what I mean. C02 isn’t the only greenhouse gas of course but I use it here just for simplicity. Just about all other greenhouse gasses have increased too though, mostly because of human activities.

I say that the increase in greenhouse gasses has caused this temperature increase. To make it clear, it’s very likely that the increase in the global temperature is due to the rise in greenhouse gasses caused by us. But anyone looking for 100% certainty is going to be disappointed. That’s not how science works – there’s never 100% certainty in anything since there could always be something out there we haven’t discovered yet which could put our theories on their heads. It’s possible that something else is causing the warming, however there’s no evidence to suggest that this is the case. Anyone who wants to say otherwise needs to show that evidence they’ve been keeping secret from the world. For years some people have tried to say it’s the sun or this is all natural warming. In the case of the sun, it can explain some of the warming from the last century (a very small amount) and in the past 35 years, the sun has actually been cooling whilst temperatures have been increasing. The climate has of course always changed throughout history. But if you want to say that the current observed warming is purely natural, then you need to account for how the extra gases we’ve produced have somehow not trapped any heat?  And if that’s not causing the warming, then what on earth could be (since we’ve established it’s not the sun)?

Nothing I’ve written here is new. But some people reading this might have not read this information before. Many people on the internet certainly still insist that we can’t possibly be warming the planet because our C02 contribution is tiny. Even supposed journalists, e.g. James Delingpole, Dominic Lawson, Donna Laframboise etc make this very basic mistake. But I guess you can find just about any belief on the internet – check out The Flat Earth Society by the way, they’ve been promoting free thinking since 1999!

You might say that was low of me, but anyone who basically denies science in this way is comparable to someone that thinks the earth is flat, because they do exactly the same thing. Don’t get me wrong , you can be as sceptical about the future impacts of climate change. You can be sceptical about spending money on renewables instead of fossil fuels. You can be sceptical about the IPCC. But you cannot deny evidence. Are we really going to have to explain to our grandchildren in 50 years that we spent well over a decade arguing about recording temperatures and elementary physics?