We live on a ball of rock.
Nothing holds it up.
Nothing needs to.
Its place in the universe is due to the star that gave it birth, the centre of its orbit, and the source of its heat and light until the end of time.
We humans are the most successful, the cleverest and most adaptable and widespread species on Earth, by a very big margin. Today, we absolutely dominate the biosphere in a way no other species has done, at least for a half-billion years, occupying or exploiting most of its ecological space.
Converting the complex living surface of the planet into a human environment rather suddenly (in a couple of centuries) has had some unintended consequences.
This is one of them:
The slow rise in the concentration of carbon dioxide in Earth's atmosphere over our "prehistoric" period - 8,000 years or so - followed by an extraordinary fast rise in the last 100 years.
The measurements were made on air trapped inside glacial ice, and are quite accurate ... you can see the range of estimates from several different Antarctic sites. Since 1958 CO2 has been monitored directly in the atmosphere with great precision.
CO2 rose about 15 parts per million by volume (ppmv) from its interglacial value of about 265 ppmv until about 1900. Since then it shot up more than 100 ppmv. It will pass 400 ppmv sometime in the year 2016 - something not seen on Earth for at least 3 million years.
Unless you have the right scientific background, this problem isn't particularly easy to understand ... but understand it we must, if we are to be any use to our grandkids. In the rest of this site, I'll try to explain it in some more detail, and show you what these kids would want us to do, if they were old enough to advocate for themselves.
On the next page I try to untangle the reasons why we are in this predicament.
This helps us to think clearly about what we have to do to fix it.
Here is something else that's accompanied human success:
The record of global mean surface temperature for the last 11,000 years ... the Holocene epoch - all of human civilization. The pink line shows the mean of estimates used to compile the record; the grey band shows the range of uncertainty for the ensemble. Zero on this scale is the mean temperature for the interval 1961-1990.
These ancient temperatures are detected in various places - old corals, tree-rings, cave stalagmites, lake floor sediments, and ice - using precise radio-chemical methods. The very steep pink line at the right is the 20th century, which is measured of course, with meteorological thermometers.
After reaching a warm plateau 8,000 years ago, the Holocene has been slowly cooling. In the last 100 years, that cooling has been reversed, and the world's temperature is climbing very steeply, compared with the natural rate of change.
Earth’s energy balance
The Earth's energy balance
Virtually all Earth's energy comes from the Sun. All Earth's radiation goes to space. But energy doesn't simply escape from the surface to space, the way it does on the Moon. Something interesting happens right next to the planetary surface. A lot of heat is transferred to and from the air, ocean & land; and lots of it circulates in the air (those fat pink arrows show how much).
In fact, a warm layer of air next to the solid surface is an essential feature of life on Earth. It's just as if our planet had a blanket all over it, holding heat beneath. The numbers give you an idea how powerful this (greenhouse) effect is.
It turns out, the strength of the atmospheric greenhouse depends precisely on the amount of CO2 in the air. This trace gas is the planet's "thermostat".
This is how much the amount of Sunlight reaching Earth varies in the course of normal solar cycles ... about 0.1%.
The modern CO2 rise and the increased atmospheric water vapour that comes with it, together exert an effect on the energy balance more than ten times greater than this. Current warming is not due to the Sun.
The problem therefore has two faces - it’s an accidental result of economic activity, and also a great injustice to the people of the future, starting with our children and grandchildren, but extending for countless generations to billions of people we will never know. It just happens to be insidious (you need scientists to tell you, otherwise you’d never know) and sluggish (it will take many centuries to develop its full effects), so we don’t find it very frightening. It also brings bad news for everyone who benefits from our use of fossil fuels (just about all of us) and extra bad news for the companies that extract and sell those fuels. Together, they are the biggest business on Earth by a long way. Quite naturally, they have resisted the idea that their products are planetary poison.
We’ve been behaving just as if we don’t know what we certainly do know.
The problem in a nutshell:
The atmosphere contained about 1,600 billion tonnes of carbon dioxide in the year 1800; humans have added ⅔ as much since ... most of it in the last 50 years.
Natural processes will eventually incorporate this carbon into Earth’s carbon cycles ... but over 100,000 years or more - not nearly fast enough for us.
Meantime it will get hotter & hotter. The time to fix this is now ... as fast as we can.
Any change in surface reflection or transmission of energy through the atmosphere must affect the temperature on Earth
Some people have said we shouldn’t be too concerned
Many Russians, for example have taken the view that their cold country stands to benefit from expanded agriculture and access to minerals in the Arctic (and a shorter, warmer winter). But in the summer of 2010 these thoughts were given a sharp corrective by the worst heat wave and drought ever, accompanied by ferocious fires and massive crop losses. A recent study by Stefan Rahmstorf and his colleagues addressed the question: how probable would this event have been without twentieth century warming? Their answer: the likelihood of such an unusual summer has risen five-fold due to extra greenhouse gases.
Another study of the terrible European heat
wave of 2003 found that, on current trends, a
summer at least as bad as that would occur
every second year by 2030 - and would be an
unusually cool one by 2060.
The fact is, there will be a few winners in a
warmer world - but overall, the damage to
human well-being will be far, far greater than
any benefits. We can be certain of this
because the human presence in the world
is so enormous and the infrastructure we
require to sustain our fantastically complex
economic arrangements is so vulnerable to instability. That ought to be the meaning of the Russian heat wave and other extreme climate events. They are the consequence of less than 1℃ of warming; there’s much more to come, and we haven’t begun to seriously address the problem.
Here’s a short list of some of the certain consequences of a warmer world
★ Heavier rain & more floods
★ Dry places (specially in the sub-tropics) will get much drier
★ A lot of agricultural land will be lost, affecting food production
★ Storms (specially tropical storms) will be more severe
★ Heat waves will be more common, severe and dangerous
★ Wildfires will be much worse
★ The sea will rise, probably for centuries, with a final level possibly tens of metres higher
★ The oceans will warm and acidify, causing very big losses of marine life
★ Many species won’t adapt to the rapid warming and will succumb
★ There are some geophysical consequences which will act as strong positive feed-backs, amplifying the warming. Nobody knows in detail what it would take to trigger them (although there are ominous signs already) but there’s potential for the warming to become unstoppable should they really get going.
A skeptical footnote
In science every claim is assessed on the evidence provided for it. Scientists are supposed to regard ALL evidence impartially, and to be good at judging which part of the evidence counts most for or against any proposition. Science is conducted as an open conversation, so that anyone can check for themselves whether a conclusion is justified. In science, having an open mind means being prepared to go where the evidence leads.
Anyone who begins with a belief, then looks for evidence to support it, ignoring the rest, is not doing science. This is the way propagandists and preachers work. It is about as unscientific as you can get.
If you investigate the problem of climate change at all, you’ll encounter many claims that seem to contradict it - for example, that warming stopped in 1998; or that warming is due to the sun; or CO₂ is harmless; or the temperature record is false; or that the severity of the problem has been exaggerated by “alarmists”, including climate scientists. I have provided answers to many of these on this site, but if you want to get detailed answers to all of them, you should use the superb site www.skepticalscience.com, which is devoted to this. I’ve given links to a number of others on the links page here.
Are scientists in serious disagreement about the climate problem?
You could easily get the impression that the scientific community is deeply divided over climate change – and indeed there are quite a few scientists who publicly and often deny that it is a problem. But it’s important to know that almost none of these is a practicing climate specialist, and many (not all) have links with either the fossil fuel industry or right-wing political institutes. By itself, that does not mean that they can’t be right – on the other hand, since this is an expert matter, dissent would count much more if it came from amongst those experts. So how much do they disagree?
Naomi Oreskes, History of Science Professor at the University of California, San Diego, did a study in 2004 to answer this question. [Use the link to read it] By examining a sample of nearly 1000 peer-reviewed papers published in the major journals between 1993 & 2003 she showed that no working scientist – not one – could be found who disputed the basic propositions of anthropogenic (man-made) climate change.
Among the people in the best position to know and understand, there is no disagreement whatsoever.
So where’s the argument coming from? It turns out that it is a fairly recent thing. It started after the US delegation signed the Earth Summit Treaty in Rio in 1992, while that country was deliberating its commitment to the Kyoto protocol. It is highly political and emotive, rather than scientific, and the arguments used to oppose climate change action are easily answered and have been refuted over & over by concerned and patient scientists. Yet they continue. You shouldn’t be surprised to know that Oreskes’ study too has been attacked by the same people. She and Erik Conway have since written an excellent book about the origins of the climate denial movement [Merchants of Doubt. 2010; Bloomsbury].
John Cook has done an exhaustive update and confirmation of Oreskes study, which you can find here.
Several recent studies have shown how very unusual these severe heat waves are, and how they will become much more common in future.
See, for example,
Nobody has ever lived in a warmer world, so how can we be sure what it will be like?
Some people say this isn't much of a problem because it's no different to episodes of past natural climate change.
They are wrong.
When was the last time CO2 was 400 ppm (where it will be in 2016)?
About 3 million years ago.
When was the last time CO2 was sustained between 400 & 425 ppm (where it will be during the 2020s)?
About 15 million years ago.
What was the world like then?
That era (the middle Miocene) was about 3℃ warmer than now; the sea was 25-40 metres higher; there was no ice in the northern hemisphere.
When was the last time CO2 increased as fast as it is now?
Nothing comparable has been found in the climate record. As far as we can tell, the present rapid rise is unique.
The climate problem is often misrepresented. It isn't really about the air getting a couple of degrees warmer ...
it's about solar energy that can't escape, and all the consequences of adding energy to the surface of the Earth.