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Asked by becky1997 to Katy, Nathalie, Paula on 24 Jun 2010 in Categories: General.
Question: What is the greenhouse effect, and is it affecting our climate? Are greenhouse gases increasing? is the climate warming? Are El Niños related to Global Warming? Is the hydrological cycle (evaporation and precipitation) changing? Is the atmospheric/oceanic circulation changing? Is the climate becoming more variable or extreme? How important are these changes in a longer-term context? Is sea level rising? Can the observed changes be explained by natural variability, including changes in solar output? What about the future?
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Nathalie Pettorelli answered on 24 Jun 2010:
Hello again 🙂
Greenhouse effect is due to increasing concentrations of greenhouse gas such as dioxyde carbon in the atmosphere – these increases are linked to human activity. These increases are linked to our planet becoming warmer on average, the now famous “climate change”. There is no doubt that human activity affect the climate, and that our climate is changing – springs start earlier in Europe, average temperature on earth has increased by nearly a degree within a 100 years. And this has consequences on wildlife too – earlier migration dates for many birds, earlier average dates for laying eggs, etc etc..Solar cycles can also affect our climate, modulating the effect of greenhouse effect on our climate
Climate change is linked to three main consequences: higher average temperature on earth, higher frequency of extreme climate events (such as storms, hurricanes, droughts), and changes in seasonal patterns (springs starting earlier in some areas of the world, seasons getting longer or shorter, etc). Because the average temperature has increased on earth, some water that was previosuly stored as ice has now joined the water cycle – and that led to sea level rising (so yes, sea level is rising)
These changes could dramatically affect life on earth – but these effects (and the importance of their consequences) will vary according to where you are (not the same consequences in Tanzania, Norway or Australia for example).
The whole scientific community is working towards understanding and predicting how our climate will change – it’s a difficult process, because there are so many parameters (such as how vegetation will react, how atmospheric and oceanic fluxes will evolve). Your best option to get the latest predictions – go to the IPCC webpage, they provide maps 😉
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Katy Mee answered on 24 Jun 2010:
Wow Becky, that’s a lot of questions!
1. The greenhouse effect refers to a build up of greenhouse gases (CO2, CH4, O3, NOx etc), which are the result of burning fossil fuels. These gases cause sloar radiation to be trapped in the Earth’s atmosphere, rather than being emitted back to space and this has caused Earth to warm up. It has allso caused other climate effects, like extremes of weather (flooding, drought, heavy snow etc). So yes, climate is still warming.
2. All of Earth’s cycles are interrelated – you can’t really separate them and this means that they will inevitably be affectd by greenhouse gases and climate change. For example, some greenhouse gases like Phosphorus can be absorbed into the oceans abd cause excessive algal growth. This in turn can restrict sunlight from reaching deeper parts of the ocean and since circulation is related to heat (warm water/air rises, cold water/air sinks), this can affect the circulation in the oceans.
3. El Nino is actually a natural phenomenon, rather than being caused by climate change, which occurs every 5 years or so and has been linked to some extreme weather event such as flooding and drought.
4. All of these anthropogenic (man-made) changes are very important because unless we try to slow down and eventually stop global warming we could damage the Earth irriversably, to the extent that we, as humans, might not be able to survive any longer (although that would be quite a way off yet)!
5. As for whether these changes can be explained by natural variation, although there is a natural variation in Earth’s climet (and thus all of the cycles you mentioned), these occur over a much greater time frame than the climate change we are experiencing due to human effects.
6. As for the future, this is a very good question! Many governments have already brought in measures to try to reduce greenhouse gases but there needs to be an international plan that every country signs up to in order to reaslly be able to combat the damage we have done. I would recommend watching the film ‘The Age of Stupid’ which is all about the impacts of global warming and what could happen in a few decades if we don’t act now….it also goes some way to suggesting a plan that we (the world as a whole) could follow in order to turn things around.
Hope that answers everything!
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Paula Salgado answered on 24 Jun 2010:
Wow, Becky, that’s like more than 10 questions in one! I’ll try to answer all…
1. Greenhouse effect is the formation of a layer of gases that stop radiation from being reflected back in to space and reflect it in all directions, including back to Earth. This means an increase in temperature, amongst other effects – like a greenhouse 😉
2. It affects our climate because it increases the average temperature at the surface
3. Greenhouse gases are increasing because most of them come from industrial production and the burning of carbon fuels like petrol. As we become more and more industrialised, we produce more of these gases.
4. There are several indications that the climate is changing and that we are seeing more extreme weather than before.
5. El Nino is a cyclic weather event that has to do with air currents in the Golf of Mexico. Some scientists believe the changes we are seeing in climate have a direct effect in the periodicity of El Nino
6 and 7. There are some evidences that the hydrological cycle and atmospheric/oceanic cycle are changing.
8. Records show that extreme weather conditions are becoming more and more frequent
9. No-one knows how these changes will impact in the future – but from most predictions and possibility studies done, it doesn’t look good…
10. Yes sea level has been rising for a while now… Just talk to people who leave in coastal, sea level areas and most will tell you they have actually seen it in there lifetime!
11. Most scientists propose that the changes we are observing are happening too fast for them to be completely unrelated to human activity. The fact is our current way of life, with all the pollution we make and the way produce energy, produces by-products can have an effect on climate – the question seems to be to what extent that effect goes
12. The future is uncertain, but most predictions indicate that if things keep changing the way they are and at the current rhythm, then it doesn’t look very good…
Phew… that was hard work! 😉
Comments
becky1997 commented on :
yes thanks Katy