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Tuesday, March 28, 2017

Sea Level Rise

• Historical sea level data derived from 23 tidegauge measurements. The bottom chart shows the average sea level since 1993 derived from global satellite measurements

• Sea level rise is associated with the thermal expansion of sea water due to climate warming (mostly) and widespread melting of land ice

• Global sea level rose about 17 centimeters in the last century. In the last decade, however, the rate of rise nearly doubled

• Sea level is not rising at the same rate everywhere on the planet. This is due to the complex dynamic effects occurring on the surface of the globe (ex: sea and surface currents, local anomalies, tides, topography ). There can be differences of more then a meter in different areas of the planet (ex: from one side to the other of the pacific ocean during the El Nino anomaly)

• The best current estimate is that the global sea level is presently rising at a rate of 3.4 mm a year and shows signs of increasing

• It is important to understand that these are the current values but that the rate of sea level rise will significantly increase as the global temperature rises

• The current estimates are mostly based on satellite monitoring. However, there are some great concerns from leading scientist and recent studies that these predictions are underestimating the rate of change to come as we still do notfully understand the dynamic of ice stored on the continents andhow it will react to rising temperatures. It appears that ice ismelting from below which cannot be picked up by satellite.

Source of Information : Climate Change: A Silent Threat by Sylvain Richer de Forges
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Monday, March 27, 2017

Indicators Of Past Climate

The CO2-temperature correlation

• The information's collected from the Paleoclimatic studies have produced (separately) two sets of graphs. One of which represents the levels of carbon dioxide in the atmosphere and another atmospheric temperatures. The age of the samples taken can be measured accurately using isotopic dating

• These graphs clearly indicate the relationship between the level of carbon dioxide (CO2) in the atmosphere and global temperatures are closely correlated

• This is yet again strong evidence that observed climate change is mainly caused by human activity through the addition of greenhouse gases (mostly CO2) into the atmosphere

• CO2 is not the only greenhouse gas (it neither has the strongest warming potential) but considering that it is largely predominant in the atmosphere comparatively with other greenhouse gases it is presently the most to blame for global warming.

Source of Information : Climate Change: A Silent Threat by Sylvain Richer de Forges
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Sunday, March 26, 2017

Indicators Of Past Climate, Paleoclimatology

• Paleoclimatology is the study of past climate, for times prior to instrumental weather measurements.
Paleoclimatologists use clues from natural "proxy" sources such as tree rings, ice cores, corals, and ocean and lake sediments to understand natural climate variability

• From this proxy scientist are able to obtain precise information's on the past climate by reconstructing past temperatures and atmospheric CO2 content on a year by year basis

• For example, ice cores removed from 2 miles deep in the Antarctic contain atmospheric samples trapped in tiny air bubbles that date as far back as 650,000 years. These samples have allowed scientists to construct a precise historical record of greenhouse gas concentration stretching back hundreds of thousands of years

• Similar techniques can also be used to reconstruct the temperature of the past oceans from corals

• These information's collected from Paleoclimatic studies have been very useful in reconstructing our past climate and confirming some hints such as the correlation between levels of GHG in the atmosphere and the global surface temperature of the earth

Source of Information : Climate Change: A Silent Threat by Sylvain Richer de Forges
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Saturday, March 25, 2017

Warnings Of A Changing Climate: A Global View

• The science of climate change has made a lot of progress over the last decades. The predictions on climate change do not come from a few individuals but from a large number of leading scientists all over the world undertaking research in different fields from geological/biological surveys to atmospheric monitoring (In 1988 the IPCC was created for this purpose)

• All the data collected from these different fields and independent studies point to the same conclusion that our climate is rapidly changing at an unprecedented rate mostly due to the action of man

• There are two levels of evidences for climate change: one which is a long term trend (the most reliable) and evidences which are already happening within our lifespan. We are starting to observe noticeable evidences and signs of climate change happening at present which are a growing concern as their frequency and strength are predicted to increase significantly throughout the century

Heat Waves
In 2003 Europe experienced the hottest summers on record causing widespread drought claiming the lives of over 30,000 people. In 2009 the state of Victoria in Australia has seen its highest temperatures ever recorded (>27°C) which facilitated the spread of the worst and most deadly fires in its recent history.

Storms
More intense and frequent storms. In 2005 Hurricane Katrina swept the US Coast as a Category 5 Hurricane. 2008 was the most active hurricane season in US recorded history

Floods
In 2008 India experienced its strongest monsoon in 50 years causing widespread floods and displacing millions of people

Droughts
2008 Australia experienced its worst drought in a century which affected food prices around the world

Source of Information : Climate Change: A Silent Threat by Sylvain Richer de Forges
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Friday, March 24, 2017

Cause Of Current Warming: Deforestation And Climate Change

• Greenhouse gas emissions from fossil fuels is by far the main cause of global warming (natural forcing included)

• However, deforestation is also an important factor which has serious implications for long term sustainability of our climate system (and biodiversity)

• Deforestation plays on two different levels:
-The loss of CO2 uptake by forests depletion and therefore the increase in global CO2 levels
- The decay of organic matter and the release of significant amounts of methane (a strong GHG gas) in the process

• Deforestation mostly comes from cutting down trees for commercial and heating purposes, fires, pollution (acid rains, soil and air pollution); mining; extreme events; melting of the permafrost.

• Massive reforestation would be a relatively inexpensiv way to limit the impacts of climate change (limit the increase of GHG and soil erosion)

• Mangroves are amongst the most efficient trees for the storage of GHG. However, mangroves around the world are rapidly vanishing.

Source of Information : Climate Change: A Silent Threat by Sylvain Richer de Forges
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Thursday, March 23, 2017

Cause Of Current Warming: Greenhouse Gases: Sources

• Global GHG emissions due to human activities have grown since pre-industrial times, with an increase of 70% between 1970 and 20046

• The largest growth in GHG emissions between 1970 and 2004 has come from energy supply, transport and industry, while residential and commercial buildings, forestry (including deforestation) and agriculture sectors have been growing at a lower rate

• Global atmospheric concentrations of CO2, CH4 and N2O have increased remarkably as a result of human activities since 1750 and now far exceed pre-industrial values determined from ice cores spanning many thousands of years

• As indicated on the left graphics, more than half of global GHG emissions come from CO2 of which annual emissions have grown between 1970 and 2004 by about 80%

• Deforestations is the second largest source of CO2 emissions

• Energy supply and Industry remain the 2 major sources of GHG

• Forestry, agriculture and transport are also major sources

Source of Information : Climate Change: A Silent Threat by Sylvain Richer de Forges
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Wednesday, March 22, 2017

Cause Of Present Warming: Greenhouse Gases

What is the warming potential of Greenhouse Gases?

• All greenhouse gases (GHG) do not have the same warming potential neither will they remain in the atmosphere for the same amount of time. This means that with the same amount of gas released into the atmosphere, some will have a much greater warming impact than other GHG

• Presently the main anthropogenic gas responsible for global warming is carbon dioxide (CO2) due to the very large amount released. However, other gases, such as methane (CH4), have a much greater warming potential but are currently released to a much lower extent (or in much lower concentrations)

• Scientists predict that the current warming of the atmosphere could trigger the release of large amounts of much stronger greenhouse gases, (such as methane CH4) from land fields and ocean beds.


What is the warming potential of Greenhouse Gases?
• Scientists predict that the current warming of the atmosphere could trigger the release of large amounts of much stronger greenhouse gases, (such as methane CH4) from land fields and ocean beds.

• For convenience, scientists use carbon dioxide as a reference and the warming potential of other greenhouse gases is expressed in terms of CO2 equivalent (As such, CO2 is said to have a warming potential of 1)

• For instance methane (CH4) is 21 times more efficient at warming the atmosphere than carbon dioxide (CO2) while Halogenated Chloro Fluorocarbon (HCF-23) is 11,700 More efficient!

• Ones released into the atmosphere, carbon dioxide will remain there for 50 to 200 years while methane will only remain about 12 years and CF 50,000 years!

Source of Information : Climate Change: A Silent Threat by Sylvain Richer de Forges
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Tuesday, March 21, 2017

Cause Of Present Warming: Principal Greenhouse Gases

Which are the main greenhouse gases?

• Water Vapor (H2O) : The most abundant greenhouse gas, but importantly, it acts as a feedback to the climate. Water vapor increases as the Earth's atmosphere warms, but so does the possibility of clouds and precipitation, making these some of the most important feedback mechanisms to the greenhouse effect

• Carbon Dioxide (CO2) : Carbon dioxide enters the atmosphere through the burning of fossil fuels (oil, natural gas, and coal), solid waste, trees and wood products, and also as a result of other chemical reactions (e.g., manufacture of cement). Carbon dioxide is also removed from the atmosphere (or “sequestered”) when it is absorbed by plants as part of the biological carbon cycle or absorbed by the ocean which acts as a dumper

• Methane (CH4) : Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from livestock and other agricultural practices and by the decay of organic waste in municipal solid waste landfills

• Nitrous Oxides (NOX) : Nitrous oxide is emitted during agricultural and industrial activities, as well as during combustion of fossil fuels and solid waste

• Fluorinated Gases : Hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride are synthetic, powerful greenhouse gases that are emitted from a variety of industrial processes. Fluorinated gases are sometimes used as substitutes for ozone-depleting substances (i.e., CFCs, HCFCs and halons). These gases are typically emitted in smaller quantities, but because they are potent greenhouse gases, they are sometimes referred to as High Global Warming Potential gases (“High GWP gases”)

Our understanding of the physical principals behind the greenhouse effect makes it undeniable that added man made greenhouse gases are causing most of the current warming and that the
temperature rise is proportional to the amount of GHG present in the atmosphere The burning of fossil fuel, which generates the emission of greenhouse gases into the atmosphere, is making the
greenhouse effect increasing stronger. One can imagine the earth as a planet surounded by a giant greenhouse (sphere of glass) and imagine what it would be like to live in such conditions. The addition of greenhouse gases in the atmosphere makes it behave more and more like a glass greenhouse. As a result of this process the earth is getting warmer and warmer.

Source of Information : Climate Change: A Silent Threat by Sylvain Richer de Forges
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