Global Warmng : What We Can Do ?

The evidence that humans are causing global warming is strong, but the question of what to do about it remains controversial. Economics, sociology, and politics are all important factors in planning for the future.

Even if we stopped emitting greenhouse gases (GHGs) today, the Earth would still warm by another degree Fahrenheit or so. But what we do from today forward makes a big difference.  Depending on our choices, scientists predict that the Earth could eventually warm by as little as 2.5 degrees or as much as 10 degrees Fahrenheit.

A commonly cited goal is to stabilize GHG concentrations around 450-550 parts per million (ppm), or about twice pre-industrial levels. This is the point at which many believe the most damaging impacts of climate change can be avoided.  Current concentrations are about 380 ppm, which means there isn't much time to lose.  According to the IPCC, we'd have to reduce GHG emissions by 50% to 80% of what they're on track to be in the next century to reach this level.

Is this possible?

Many people and governments are already working hard to cut greenhouse gases, and everyone can help.

Researchers Stephen Pacala and Robert Socolow at Princeton University have suggested one approach that they call "stabilization wedges." This means reducing GHG emissions from a variety of sources with technologies available in the next few decades, rather than relying on an enormous change in a single area.  They suggest 7 wedges that could each reduce emissions, and all of them together could hold emissions at approximately current levels for the next 50 years, putting us on a potential path to stabilize around 500 ppm.

There are many possible wedges, including improvements to energy efficiency and vehicle fuel economy (so less energy has to be produced), and increases in wind and solar power, hydrogen produced from renewable sources, biofuels (produced from crops), natural gas, and nuclear power.  There is also the potential to capture the carbon dioxide emitted from fossil fuels and store it underground—a process called "carbon sequestration."

In addition to reducing the gases we emit to the atmosphere, we can also increase the amount of gases we take out of the atmosphere.  Plants and trees absorb CO2 as they grow, "sequestering" carbon naturally.  Increasing forestlands and making changes to the way we farm could increase the amount of carbon we're storing.

Some of these technologies have drawbacks, and different communities will make different decisions about how to power their lives, but the good news is that there are a variety of options to put us on a path toward a stable climate.

published by NATIONAL GEOGRAPHIC

image by : Paul Nicklen

Climate Changes

Climate change can be considered at two board temporal scale : long-term changes at greater  than 20.000 years, and short-terms changes between 100 and 20.000 years. Climate variabelity refers to mainly to decade to decade and year to year changes. Causes of climate change can be classified as either external or internal.  The former includes changes of earth’s orbital geometry, often referred to as Milancovitch or astronomical variations. Internal  causes result from changes to the basic nature of the components of the climate system and feedbacks between these components.

Currently there is the great concern about human-induced climate change mainly due to increased global pollution levels which have, through an enchanced greenhouse effect, the potential to increase the global temperatures, alter climate patters and raise sea levels. At the local to regional scale, deforestation and desertification are also of concern. Although the mangitude of climate change in the tropics is likely to be less than at higher latitudes, climate changes impacts will considerable. A full understanding of the gravity oh these changes will, however, only be achieved when the causes, nature and availability of climate resources in the tropics is fully appreciated. This will continue to be one of the main goals of tropical climatology.

Sources : McGregor, Glenn. 1998.Tropical Climate 2nd ed.Baffinslane : John willey and Sons