Climate : What do we really know about global warming?

Climate

What do we really know about global warming?

Melting glaciers, increasing droughts and floods - how do we tell the difference between natural variation and human-induced climate change?

Professor Mojib Latif, an internationally recognized climate expert, member of the Intergovernmental Panel on Climate Change (IPCC), and author of the new book "Global Warming. He explained the difference between natural phenomena and human induced environmental changes in an interview with DW.

DW: In spite of reports of rising CO2 emissions and warnings that political efforts are not doing enough to halt global warming, there are still people who doubt that human activities are driving climate change. Why?
Mojib Latif: The problem is that people have difficulties differentiating between natural climate variation and the long-term warming trend which is being influenced by humankind. And certain people exploit this to sow doubt about whether there is such a thing as anthropogenic or human-influenced climate change.
How easy is to distinguish between the natural climate variation going on in the background all the time and human-made climate change?
It's not that easy. That's why it's important for us to investigate natural climate variation. We climate researchers don't just concentrate on the human influences. We use something you could compare with finger-printing to identify which variables have an effect on the climate. Every human being is unique because of his or her fingerprint and the same applies to the various factors which influence the climate. For instance human-induced warming heats up the lower layers of air, but at the same time cools the higher layers, up at an altitude of 20 or 30 kilometers (12.5 to 18.6 miles) or higher. Now the influence of solar radiation, for example, would not do that. Another factor is the time-scale. Global warming is developing in proportion to the increase of carbon dioxide. Solar radiation has actually diminished in the last 50 years, so it simply cannot explain the warming that has taken place in the last few decades.

"We live in a media society, where things that are out-of-the-ordinary attract interest," said Latif.

Nevertheless, books and articles published earlier this year claiming exactly that have attracted a lot of interest. Can you explain that?
We live in a media society, where things that are out-of-the-ordinary attract interest. There is a broad international scientific consensus that we humans are influencing the climate and are in the process of changing it in a way that is unprecedented in the history of man, unless we change track. But it's comparatively boring if you hear that every day. That's why somebody who maintains exactly the opposite attracts huge media attention. People need to have a sound knowledge of the basic facts to avoid being misled by this kind of thing.
Why do you think there are still so many so-called climate skeptics?
A lot of people are afraid that the change to new technologies, renewable energy, will jeopardize their prosperity. That's not the case. We can actually see that Germany has benefitted from investing in renewables in recent years. Of course there are lobby groups who have no interest in changing things in the short term because they want to maximize their own profits, for instance the energy and car industries. It's up to the politicians to set up long-term frameworks so that these companies can be prepared for the fact that they have to change in the long term.
Some people say we're not ready yet to do without oil and coal?
We have to do it, because fossil fuels like oil and gas are finite. And the sooner we manage to adapt our economic structures to renewable energies the better, not least from an economic point of view. We have to keep reiterating that this is not "just" about climate. It's about the future of the human race and our prosperity, which we can only hold on to if we make more use of renewable energies.
Climate is influenced by very complex mechanisms and it is extremely difficult to forecast the impacts. Some of the critics use that argument to talk down the risks or the need for urgent action. They accuse scientists and politicians of unnecessary panic and say we still have time to wait and see.
Well of course there is some uncertainty. There always is in science. But we know enough. We know the Earth is warming; we know the ice is melting; we know sea level is rising. So the indications are all there, and it would go against our normal behavior based on experience not to take these warning signs seriously. If the chance of being knocked down by a car were 50-50, nobody would cross the street. So why is it that with the climate or environmental issues in general we insist on a 100 percent probability? That makes no sense.
What does that mean in terms of climate adaptation, especially in the poorer areas of the world which are under threat?
We are going to experience continuing climate change, whatever we do, because the Earth's system takes time to react. That's why we have to invest in adaptation, especially in poorer countries. We also have to help these countries to develop sustainably, so that they don't make the same mistakes we made 100 years ago.
Can the measures currently being envisaged by politicians suffice to keep to the 2-degree Celsius goal?
The 2-degree goal means the earth's temperature should not rise by more than two degrees Celsius (3.6 degrees Fahrenheit) by the end of the century, compared with the temperature before industrialization. We already have 0.7 degrees of warming, the system is still adapting to past emissions, so keeping to two degrees is already a major challenge. Unless something changes very fast at the climate conferences and the Americans especially agree to binding emission reduction targets, I don't believe we can make it. And even two degrees would be a considerable rise. It would take us into conditions unprecedented in the history of man.
Interview: Irene Quaile
Editor: Jessie Wingard