Arquivo de etiquetas: 2ºC

The Basics of Climate Change Science V

Recent History of Climate Change

We’ve been looking at climate science, at the Greenhouse Effect, at greenhouse gases, at other drivers of climate change–inter-annual, decadal, even we’ve talked briefly about the long term geological changes caused by changes in the earth’s orbital. We’re living in real time right now where we’re already experiencing significant climate change and the human-induced component of that is our preeminent worry. We know that the greenhouse gas effect is powerful; it is already present. It is responsible for raising the earth’s temperature compared to the preindustrial level by almost one degree Celsius or almost 1.8 degrees Fahrenheit and we know that we’re on a trajectory of great danger.

We’re going to talk in future lectures in detail about impacts and about why we care about the two degree centigrade limit agreed in Copenhagen and Cancun as a reflection of or a definition in need of avoiding dangerous interference in the climate system.

I want to mention briefly some of the things that we’re currently observing, and I want to start with the quite remarkable set of maps produced by my quite wonderful colleague, Professor James Hansen. You’ll recall Dr. Hansen testifying in 1998 to the U.S. Congress giving the Congress the first authoritative warning “This is real; it’s coming”, and Dr. Hansen called it correctly–he’s a brilliant global climate scientist, who has been studying every aspect of the underlying physics–the radiative forcing, the earth’s dynamics with remarkable perspicacity for decades.


He’s been telling us we’re already in the midst of deep change, and a quite remarkable way that he has demonstrated this is shown by this set of nine maps. If you focus in on the map in the upper left hand corner, you can see through the blotches of color a world map. This particular world map is for the year 1955. What Professor Hansen has done is to take the average temperature in each part of the world, each pixel on the map, each location on the map and calculated the average for the years 1951 to 1980, and a kind of bell-shaped curve of temperatures in that place during that time interval.

Well, you know what a bell-shaped curve is or a normal or Gaussian curve. It shows the probability of falling above or below the average temperature line, and we say that in the tails of that bell-shaped curve those are when you have big deviations from the average outcome either on the plus side that something is much larger than average or on the other tail of the distribution when something is much less than average. So, say that for the years 1951 to 1980, you have a bell-shaped curve of temperature in a particular place, but a few years are really warm and a few years are really cold–those are the outliers; those would be at the tails of the normal distribution.

Now, events that are two standard deviations above the average or two standard deviations below the average are at the outer tails, and the plus/minus two standard deviations in total accounts for about 5% of the occurrences. Three standard deviations out is an absolutely extraordinary case that happens only a couple of times every thousand occurrences.

So, Professor Hansen said, “Suppose we know the normal distribution of temperatures in each part of the world based on what we observed from the period 1951 to 1980 and suppose we define a really extreme event as a three-standard-deviation outlier–super hot or super cold.” Well during the period where you calculate that, 1951 to 1980, that wouldn’t happen very much by construction that would only happen a couple times out of a thousand, but Professor Hansen wanted to ask the question “are such extreme events, real outliers, occurring with more frequency?”

So he made maps that showed when different parts of the world had extreme temperature events either extreme hot, which is shown in dark maroon here, or extreme cold, which is shown in purple on the map, and if you look back at 1955, there are a couple tiny spots just by random that happen to have extreme heat waves.

You can see around Hudson Bay in northern Canada or maybe just a part of northern Spain had a real heat wave during the summer months of June, July, August of 1955, but the map as a whole doesn’t show anything very extraordinary. Most of the temperatures lie well within plus or minus two standard deviations of the normal temperature for that particular place.

Professor Hansen has made this map for every year. If we go to the central column at the top row; that’s for the year 1965. I don’t see any dark maroon here. There isn’t any single part of the planet in the year 1965 that for the Northern Hemisphere summer months had an extreme heat wave. Well, that’s natural. These extremes are very very rare by definition because he constructed the definition of extreme to happen very rarely during the period 1951 to 1980. 1975, well again, focus in extreme northern Canada pretty hot, unusual; the rest of the world, nothing too much special. Now, move the calendar forward to our time. Professor Hansen is making a point: what used to be extreme is becoming normal.252

This is really the shock for the planet. Look at 2006. All of a sudden the map looks nothing like the 1955 or 1965 or 1975 map; there’s red all over the place; in the Indian ocean, in North Africa, in the Northeast of the US and Canada. Red blotches all over the map! They weren’t there before. What he’s saying is that in 2006 by the standards of the historical period of 1951 to 1980, suddenly we’re finding ourselves in the tail of the distribution on the hot end of what used to be the distribution in which such events would be very rare, so stay with the bell-shaped curve of 1951 to 1980, stay with the same definition of extreme heat, all of a sudden it’s happening in many parts of the world. 2007: red, red, red blotches! 2009: oh my word!

Looks like half the world’s experiencing extraordinary three-standard-deviation heat waves because that was an absolute again period of this increase in hot temperatures and what we’re seeing is the core message; what used to be extraordinary is becoming normal not normal pleasant, normal unpleasant. What used to be an extreme heat wave that happened maybe one time in a thousand or two times in a thousand is now happening fifty times in a thousand, 5% of the time, or a hundred times in a thousand, 10% of the time. The extremes are the new normal. We shouldn’t take that as normal.

We should take that as an alarming reality because of what is shown in the next graph. These are data produced by the insurance companies. They need to know what happens with disasters because they pay out when disasters occur. They have to price their contracts, and what they are recording is a massive increase of disasters and especially not so much the disasters we don’t cause, although maybe some of them are better measured or there are more people living in places, say, hit by earthquakes, but the disasters that can be changed in frequency and intensity by global, anthropogenic climate change–the so called hydro-meteorological disasters: the extreme storms, the extreme tropical cyclones like typhoon Haiyan or superstorm Sandy or the massive droughts afflicting much of the world today in Brazil, California, parts of Australia, parts of India, parts of Pakistan, or the massive flooding.

These are the kinds that the insurance companies are noting because they’re making payouts and they are realizing that we’re having a huge rise of hydro-meteorological disasters. Well, we have looked earlier and Emmanuel Guerin in the next lecture is going to look in detail at some of the impacts, I just want to reflect on 2014–our year, our current period. If you happen to be a tennis-lover and you were watching the Australian Open at the beginning of the year, you were watching tennis players playing under nearly impossible conditions–massive heat wave as shown in this map for January 2014. Australia was hit by one of these extraordinary heat waves that have become the new normal.253

Here’s a different map for the spring of this year. California experiencing a state-wide drought and a very significant part of California experiencing the most intense and remarkable drought  leading to normal water reservoirs used for irrigation and drinking water dropping to absolutely frightening proportions. And as I’ve shown earlier, Brazil the same, Indonesia the same.

When I was in Istanbul earlier this year, the reports of major drought around the Istanbul area. A water reservoir shown here with the water basically gone and incidentally, hit by, Istanbul hit by massive flooding a couple of months later. Not unexpected or paradoxical. Droughts followed by floods, precipitation patterns characterized by extreme storm events with very heavy downfalls when the downfalls occur and in Bosnia, Herzegovina, and in Serbia in the spring, it was shocking. I arrived in Serbia just after these floods. These were not one-in-a-century floods; these were basically characterized as one-in-five-hundred-years or one-in-the-millennium flooding.254

They’d never seen the extent of this kind of flooding and tremendous property loss and many people lost their lives. In my work as special adviser to Secretary General Ban Ki-Moon on the Millennium Development Goals, I work in a lot of the poorest places in the world and not by coincidence many of those are dryland environments; places where rainfall is so marginal that getting a crop in particular year is always a risk; it is always a bit of a gamble–will the rains fail? These drylands stretch across the Sahill of West Africa to the horn of Africa–Ethiopia, Sudan, northern Uganda, Kenya, Somalia; they stretch across the Red Sea into the Arabian Peninsula into Yemen, Oman, Saudi Arabia; they stretch into western Asia–Iraq, Iran–and into central Asia–Afghanistan and neighboring countries. And that whole swath of thousands and thousands of kilometers and so many millions of people living in vulnerability face the ever-present risk that the rainy season is going to fail.

They’re already dry, and climate change for many of these places is already a clear and present danger and a taker of lives when these droughts and ensuing famines occur. Now, one of the things that I also see in my UN capacity is that not only do these droughts and crop failures lead to huge suffering, but they are themselves the tinderbox that can lead to conflict.

When people are hungry, when people are desperate, demigods, dangerous people absolutely can sway unemployed, desperate, hungry young men or just force them into paramilitaries and the consequences now shown statistically with great care that when the rains fail and poor regions, especially in Sub-Saharan Africa, conflicts are likely to follow. One of the most horrific conflicts on the whole planet now is in Syria. Syria is part of the Mediterranean environment, which the climate models tell us is already a drying region that is likely to get much dryer in the future. This is by virtue of the Mediterranean location in the world climate system. Warm, dry air is now descending on the Mediterranean decreasing the amount of rainfall that is coming.

Well, all through the Mediterranean Basin there has been a drop of rainfall over the last twenty years, but in Syria, there was nearly ten years of continuous drought and over time, one year of drought may be manageable, two years of drought-very hard to get a crop, three years of drought-the soils lack all moisture and the crops start to fail, populations start to move, farm families can’t survive, people abandon their homesteads and in very complex, not well-governed places when people move, frictions explode, frustrations, hunger, and of course desperation also take off. I remember in Syria in 2007-2008-2009 the United Nations was putting out alarms. We’ve got major drought, major population movements, major food insecurity.

Nothing much was done because the world doesn’t respond to these kinds of warnings nor did the government, an authoritarian government capable of great brutality and lack of responsiveness and also being overwhelmed by chronic, nearly decade-long drought. What was the consequence? Well, drought wasn’t THE cause of Syria’s conflict, but one can say that drought and food scarcity, soaring food prices, hungry people, displaced populations were part of the complex mix of bad governance, frustration, corruption that meant in 2011 when the so-called “Arab Spring” erupted in Tunisia and Egypt, protests began massively in Syria.

The Assad regime cracked down on those protestors, a military insurgency broke away from the Syrian Army, and then as one thing leads to another, suddenly there was support coming from outside powers—the United States, Turkey, Saudi Arabia supporting the insurgency. There was Russia and Iran supporting the Assad regime and suddenly drought, famine, food insecurity, and the other factors erupted into violence; violence into war; war into proxy war; and soon enough by now more than 160,000 people dead and disaster and still a completely unresolved and indeed spreading war. I mention this because climate change is gonna have many impacts and it’s going to have the kinds of impacts that Emmanuel will be talking about in the coming lectures, but we should understand that human capacity, we have it to adjust sometimes, sometimes we’re able to counteract these kinds of events, sometimes we’re able to use our intelligence and our smarts to get ahead of the curve, sometimes we are just dumber than dumb.

The visceral emotions, the hate, the fear, the arms take over and what begins as an ecological crisis turns into a full-fledged human disaster, war, threat of ever-widening proportions. The point is climate change is going to have massive impacts on the planet, and we have to learn to think ahead and think cooperatively if this is not to get the best of us. Well, in this course we are not going to be examining in detail how we can do that, how we can use our intelligence, our technology, our know-how, and the global tools of cooperation in the UN Framework Convention on Climate Change to get ahead of the curve.

By the end of this course, I hope we have the tools so that when we enter the next semester as delegates to the global, online negotiations, we’ll be able to find the path forward and help to illuminate the ways that we don’t end in this kind of disaster but rather find a way to cooperation, to peace, and to security for everybody.