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S. Chatterjee and A. Tandon
Keywords Climate change · Air quality · Climate incidents · Eco-biological
effects · Climate migration · Socio-economic effect
1 Climate Change—A Myth, Hype or a Reality?
Climate change refers to significant and lasting changes in the statistical distribution
of weather parameters, e.g. in air temperature, precipitation, wind patterns etc. In a
much simpler view, “climate change” refers to any change of the classical 30-year
climatology, regardless of its causes. According to Inter-governmental Panel on Climate Change (IPCC), often “climate change” denotes only those variations caused
by human activities, whereas, changes due to natural variations are referred “climate variations” (IPCC 1995). Global scientific community has a near unanimous
consensus that anthropogenic emission of greenhouse gases and thus their rising
atmospheric concentration are causing global warming and other climatic changes.
According to the IPCC, global average annual mean surface air-temperature is projected to rise between 1.4 and 5.8 °C by 2100, based upon the findings of leading
modelling groups around the world (IPCC 2001). Studies carried out over the past
two decades elucidated that Earth’s climate will change in response to accrual of
greenhouse gases in the lower atmosphere. The unusually rapid temperature rise
since the mid-1970s to the tune of 0.5 °C is considerably attributable to this anthropogenic rise in the concentration of greenhouse gases (IPCC 2001; Trenberth 2001).
We have already seen various effects of this recent warming on non-human systems
(Easterling et al. 2000; Malhi and Phillips 2004; Parmesan and Yohe 2003; Rignot
et al. 2003; Root et al. 2003; Thompson et al. 2002; White et al. 2005). Due to very
long residence time of greenhouse gases in lower atmosphere, the climate system’s
inertia, climate change would continue for at least several decades even if radical
preventative actions are taken now (Houghton 2004; IPCC 2001). There has been a
debate about the present quantum and future trajectories for anthropogenic emissions
of greenhouse gases. It is obvious that there are uncertainties about the sensitivity
of the climate system to future changes because atmospheric composition of these
greenhouse gases (normally present in the atmosphere) is in parts per million or
parts per billion fractional (volume) concentration levels. The range in the predicted
rise in global average annual mean surface air temperature (1.4–5.8 °C) by 2100
indicates both uncertainty about future emissions of greenhouse gases and marginal
differences in design of the several leading global climate models. The spatial distribution pattern of projected temperature and particularly change of rainfall also
differ between these integrated/coupled global climate models. Therefore, reported
estimates of climate changes over coming decades are indicative rather than predictive (IPCC 2001). It is worthy to mention here that the uncertainty is symmetrical.
So, an underestimation of future climate change is as likely as an overestimation.
It can be stated with considerable confidence that in longer-term, the probability of
exceeding critical thresholds i.e. causing sheer-changes in climate, environment and
related effects will definitely rise (Houghton 2004; IPCC 2001).
S. Chatterjee and A. Tandon
Keywords Climate change · Air quality · Climate incidents · Eco-biological
effects · Climate migration · Socio-economic effect
1 Climate Change—A Myth, Hype or a Reality?
Climate change refers to significant and lasting changes in the statistical distribution
of weather parameters, e.g. in air temperature, precipitation, wind patterns etc. In a
much simpler view, “climate change” refers to any change of the classical 30-year
climatology, regardless of its causes. According to Inter-governmental Panel on Climate Change (IPCC), often “climate change” denotes only those variations caused
by human activities, whereas, changes due to natural variations are referred “climate variations” (IPCC 1995). Global scientific community has a near unanimous
consensus that anthropogenic emission of greenhouse gases and thus their rising
atmospheric concentration are causing global warming and other climatic changes.
According to the IPCC, global average annual mean surface air-temperature is projected to rise between 1.4 and 5.8 °C by 2100, based upon the findings of leading
modelling groups around the world (IPCC 2001). Studies carried out over the past
two decades elucidated that Earth’s climate will change in response to accrual of
greenhouse gases in the lower atmosphere. The unusually rapid temperature rise
since the mid-1970s to the tune of 0.5 °C is considerably attributable to this anthropogenic rise in the concentration of greenhouse gases (IPCC 2001; Trenberth 2001).
We have already seen various effects of this recent warming on non-human systems
(Easterling et al. 2000; Malhi and Phillips 2004; Parmesan and Yohe 2003; Rignot
et al. 2003; Root et al. 2003; Thompson et al. 2002; White et al. 2005). Due to very
long residence time of greenhouse gases in lower atmosphere, the climate system’s
inertia, climate change would continue for at least several decades even if radical
preventative actions are taken now (Houghton 2004; IPCC 2001). There has been a
debate about the present quantum and future trajectories for anthropogenic emissions
of greenhouse gases. It is obvious that there are uncertainties about the sensitivity
of the climate system to future changes because atmospheric composition of these
greenhouse gases (normally present in the atmosphere) is in parts per million or
parts per billion fractional (volume) concentration levels. The range in the predicted
rise in global average annual mean surface air temperature (1.4–5.8 °C) by 2100
indicates both uncertainty about future emissions of greenhouse gases and marginal
differences in design of the several leading global climate models. The spatial distribution pattern of projected temperature and particularly change of rainfall also
differ between these integrated/coupled global climate models. Therefore, reported
estimates of climate changes over coming decades are indicative rather than predictive (IPCC 2001). It is worthy to mention here that the uncertainty is symmetrical.
So, an underestimation of future climate change is as likely as an overestimation.
It can be stated with considerable confidence that in longer-term, the probability of
exceeding critical thresholds i.e. causing sheer-changes in climate, environment and
related effects will definitely rise (Houghton 2004; IPCC 2001).