\section{Pakistan; Science of Climate Change and Droughts}

Pakistan has been rated amongst the 10 countries\cite{1} that are at extreme risk to climate change given their specific social, economic and environmental conditions. The most important climate change potential threats\cite{2} to Pakistan are identified as:

\begin{itemize}
\item Increased variability of monsoon;
\item Rapid recession of Hindu Kush-Karakoram-Himalayan (HKH) glaciers threatening water inflows into the Indus River
\item System (IRS); reduction in capacity of natural reservoirs due to glacier melt and rise in snow line;
\item Increased risks of floods and droughts;
\item Increased siltation of major dams resulting in greater loss of reservoir capacity;
\item Severe water-stressed and heat-stressed conditions in arid and semi-arid regions, leading to reduced agriculture productivity and power generation;
\item Increased upstream intrusion of saline water in the Indus delta, adversely affecting coastal agriculture, mangroves and breeding grounds of fish; and
\end{itemize}

For a country like Pakistan which is grappling with a long list of issues on social, economic, political and environmental fronts and where development indicators are dwindling; climate change is complicating the already prevailing challenges. These include food insecurity, unsustainable livelihood systems, shortage and abundance of water; disease burden, loss of biodiversity and environmental degradation to name but only a few. The list seems to be unending.

Pakistan has a diverse topography and environmental conditions; with high mountains in the north to coast in the south. In between there are deserts, river basins, plateaus and canal-fed and arid agricultural fields. The climate induced disasters and climactic cyclones, droughts, floods, heavy rains, heat and cold waves etc. recurrently take a heavy toll on human life, livelihoods, environment and existing development gains.

At start of the last decade, Pakistan witnessed the worst drought (1998--2002) of its history while at the end there were worst floods. This ironic tradition continued as the current decade also started with an unprecedented monsoon spell (floods 2011) followed by floods 2012. Together these three flooding events are estimated to have affected 30 million people in three consecutive years. Climatologists and environmentalists have clearly declared these events the result of climate variability.

\subsection{Past and Expected Future Climatic Changes over Pakistan}

During the last century, average annual temperature over Pakistan increased by 0.6~$^{\circ}$C, in agreement with the global trend, with the temperature increase over northern Pakistan being higher than over southern Pakistan (0.8~$^{\circ}$C versus 0.5~$^{\circ}$C). Precipitation over Pakistan also increased on the average by about 25\%.

Studies based on the ensemble outputs of several Global Circulation Models (GCMs) project that the average temperature over Pakistan will increase in the range 1.3--1.5~$^{\circ}$C by 2020s, 2.5--2.8~$^{\circ}$C by 2050s, and 3.9--4.4~$^{\circ}$C by 2080s, corresponding to an increase in average global surface temperature by 2.8--3.4~$^{\circ}$C by the turn of the 21st century. Precipitation is projected to increase slightly in summer and decrease in winter with no significant change in annual precipitation. Furthermore, it is projected that climate change will increase the variability of monsoon rains and enhance the frequency and severity of extreme events such as floods and droughts.

\subsection{Droughts}

Drought in Pakistan has become a frequent phenomenon in the country. Drought differs from other natural disasters in the sense that the effects of drought often accumulate slowly over a considerable period of time and may linger on for years even after the termination of the event. Because of this, drought is often referred to as a ``creeping phenomenon.'' The impacts of drought are less obvious and are spread over larger geographical areas than the area damaged from