Climate Science Fundamentals
We can’t ignore the fact that weather and climate and the factors that affect them are highly complex, and there are some aspects of it that aren’t fully understood. Nevertheless, there’s a large body of evidence at the core of climate science that is highly robust.
The My Climate and Me team thought that this was the best place to start.
Fact: Global temperatures are increasing
Global temperature data provides clear evidence of this. The long term trend is one of global temperatures increasing. Since 1850 global temperature has risen by 0.8°C. 2010 was the hottest year globally on record.
For a more detailed graph, click here
Climate scientists: Focus of investigation
With the increases in long-term temperatures an accepted fact, the primary focus for the world’s climate scientists for many years has been to investigate what’s causing this temperature increase.
Robust studies have been conducted into the reasons for recent high levels of global warming.
What is the most likely principal cause of this warming? Here are the primary contenders
Q: Is it variations in the earth’s orbit around the sun?
The nature of the earth’s orbit around the sun does vary over time changing the pattern of heating the earth receives. Scientists believe this is the cause of the major ices ages we’ve experienced over the last 10 million years or so. However, the timeframe of these cycles is very long – from 10,000 to 100,000 years, so they can’t explain the rapid temperature rise we’ve experienced in the last 150 years.
Met Office Climate Scientist’s say: No
Q: Can it be solar flares and sunspots?
These can have an effect on global temperatures, but recent activity levels, particularly over the last 50 years have been average, not increasing. If this factor had been driving temperatures on earth we wouldn’t have experienced an increase in global warming over the last 50 years.
Met Office Climate Scientist’s say: No
Could it be down to natural climate cycles?
The earth also experiences natural climate cycles that can have a profound effect on temperature and rainfall patterns.
Ice ages, and El Niño periods are typical examples. In the case of ice ages the impact is very slow, occuring gradually over many centuries, and in the case of El Niño it’s comparatively quick, starting and finishing within a few years.
Climate scientists have examined the effects of all known natural cycles and none of them are sustained or large enough to explain the warming over the last few decades. Natural climate cycles can add to the long-term warming trend or slow it down as we’ve seen in recent years, but they’re not significant enough to explain it.
Met Office Climate Scientist’s say: No
Which leaves the most likely cause of recent global warming, man.
Out of all the possible causes of global warming that have been analysed, the most likely cause of the rapid temperature rise over the past 150 years is man.
Man produces large quantities of CO2 primarily from burning fossil fuels. And basic physics tells us that more CO2 in the atmosphere will trap in heat that would normally escape into space.
Since the industrial revolution gathered momentum in the 1800′s human beings have emitted 1 million, million tonnes of CO2. Total annual emissions continue to increase.
CO2 is now at its highest level for 800,000 years.
Man also influences the climate through other greenhouse gases like methane (natural gas) emissions and pollution. Deforestation also has an effect. However, CO2 is the main focus for scientists because it stays in the atmosphere for a long time.
The Energy Imbalance
For our climate to remain stable, the earth needs to emit as much energy as it absorbs from the sun. Currently the earth is retaining too much energy. It’s accumulating and it’s affecting our climate.
Climate Change Conclusions
When climate scientists consider all the ‘natural factors’ that could be affecting our climate, the long-term temperature trend (green line) in the chart below is broadly flat. Introduce the effect of man-made greenhouse gases into the mix and the computer model produces a line that tracks almost directly onto the observed temperature rise.
The Scientific Consensus
Detailed investigations over the last 20 years have created high levels of consensus about the causes of global warming across the scientific community.
The IPCC (Intergovernmental Panel on Climate Change), set up by the United Nations and the World Meteorological Organisation, with over 2000 climate scientists from 154 member states provides the world’s most authoritative view on the subject. In its most recent report, the IPCC concludes:
‘Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in manmade greenhouse gas concentrations’
‘The scale and pattern of recent changes in our climate can only be explained if we include the effects of man-made greenhouse gases as well as natural causes’
New Scientific Focus
With the link between man-made CO2 and increasing global temperatures well understood, the focus of scientific study now is to address more complex questions like:
- How much is the earth going to warm by?
- Are we going to start experiencing more extreme weather like droughts and more severe storms?
- What will be the future effects of warming on the human population? Who will be worst affected?
- How will the animal and plant life be affected?
- What will the timing of these future effects be?
Met Office scientists are closely involved with all of these areas of scientific study and you can look forward to hearing a lot more about these hot topics from us, here at My Climate & Me.
could we have a more uptodate graphic on the total carbon emissions please. the graph shown stops at 2000. and it is of course now 2013
a cynical person might ask why show a graph of 5 year averages, vs say hadcrut4, or hadcrut 3?
What does a #5 year average mean, vs showing a ten year average, or just plotting annually.
a cynical person might suggest this is case of ‘hiding the hiatus’?
and an example of cherry picking graphs, whether or not that is true or not, is it not a problem that this is how this is perceived..
why not just show HadCrut4? which is more immediately accessible to the public, without an ‘explanation’ required for 5 year averages..
if it was me i would start by saying”the glabol warming has change are world”.and you ask how let me tell you how.#1 the glabol warming has change the pole’s of are world how by the warming is melting of ice ever year by 1″ a year and in some case’s were it warm it turning cold.we have to do some thing to stop it.we as humans have the God given right to change some thing if it’s not right.because if we don’t are kids and there kids wont have a place to live.so i ask you what’s is the most in-portion thing we need to do.(stop the glabol warming)fine better way’s for are fulls we us each year and better way’s to make the lives of are children better.there are so many way’s to help are self’s we just have to get ever one to see it.because we don’t we wont have a world.that’s how i would start it.give them some thing to talk about for the next week are so.you got to believe in what you are saying to them if you don’t then you have wast your time in tell them.get as much of info as you can to prove your point.well i hope that i have open your eye’s to what you have to do.your friend fred
“And basic physics tells us that more CO2 in the atmosphere will trap in heat that would normally escape into space.”
Really? I’ve looked at the standard “earth as a black body” analysis and it makes so many gross approximations and neglects so many significant factors (eg transport of heat within the atmosphere by mechanisms other than radiation) that it is, at best, a plausibility argument.
You say “[Sunspots] can have an effect on global temperatures, but recent activity levels, particularly over the last 50 years have been average, not increasing. If this factor had been driving temperatures on earth we wouldn’t have experienced an increase in global warming over the last 50 years.”
Surely your argument is fallacious?
Most people would not accept that water in a pot on the stove cannot be brought to the boil unless you continually turn up the gas.
It would be better to recognise that if the gas is kept above a certain threshold, the water will continue to heat (until it boils).
If solar magnetic fields are below a certain threshold over a prolongued period there is a possibility that the earth will cool down (assuming there is historic evidence of a link which some solar scientists believe).
Nuclear power will certainly reucde local pollution levels as compared to thermal power . But globally nobody knows.There is neither a standard scientific method which is mutually and globally accepted nor any global authority to decide whether any particular effect on a particular location is caused by global warming and not by any other factor.But nuclear power requires stringent safety standards and nuclear fuel is more scarce.