Climate related challenges are not new to Pakistan and the nation has suffered in the form of extreme floods and prolonged droughts for many decades. In a recent article, we discussed two divergent theories about climate change behind frequent and recurrent floods and droughts. One theory is based on the belief that this is a general environmental phenomenon and cycles that come and go, while the other theory believes that the challenges are due to the growing impacts of climate change. It is based on numerous scientific studies resulting in a general popularity of the belief. However, in either case, the phenomenon has great implications for the whole ecosystem and resultantly for the country. 

Climate is a prolonged state of weather that prevails over a region. Mankind has experienced a great disturbance in seasonal patterns since the advent of the Industrial Age. Basically, climate change is the variation in weather pattern that exists from centuries. It is mainly triggered by the increased emission of chlorofluorocarbons that significantly influence the water cycle. These emissions prevent heatwaves such as infrared radiations to go back to space during night to create a greenhouse effect on Earth. 
Increased anthropogenic activities are affecting metrological conditions, which lead to climate related disasters. Globally, the frequency of recurrent flooding and drought events has increased, ranking Pakistan as the 7th most vulnerable country of the world. The major consequences of climate change in Pakistan include: increase in temperature, spatial and temporal variability in precipitation, melting of glaciers, excessive erosion, decreased water storage ultimately leading towards water stress and food insecurity, degradation of biological diversity, ecosystem vulnerability, increased frequency of extreme events of floods and droughts, and seawater intrusion, etc. 
In this article, the various implications of climate change phenomenon on Pakistan are discussed.
Rise in Temperature
According to the International Panel on Climate Change (IPCC), Earth’s temperature has risen by about 1⁰C from pre-industrial level. With the business as usual scenario, this rise may reach up to 1.5⁰C during 2030-2050.¹ The rise in temperature influences the spatio-temporal distribution of air masses by changing regions of low-pressure and high-pressure systems around the globe. This shift results in seasonal variability and periods of extreme hot and cold days. Resultantly, the duration of summer season has prolonged with temperatures exceeding 50⁰C during June 2017 and 2020 over Pakistan.² The coastal city of Karachi has also witnessed one of the fatal impacts of seasonal variations in the form of heatwaves during 2015. Surprisingly, the temperature of Karachi rose up to 43⁰C and approximately 1,200 people lost their lives due to the hot and humid weather. The rise in temperature created a domino effect that is influencing other weather phenomena, particularly precipitation trends. 
Rise in Sea Level 
Pakistan has also experienced a rise in sea level at a rate of about 1.1 mm per year, which is even higher than the global mean.³ The projected scenarios show that it will continue to rise during the 21st century. In 2019, the global mean sea level was 387.6 mm higher than the average level of 1993 whereas a rise of 6.1 mm has been observed from 2018 to 2019. Rise in sea level is most likely to affect the low-lying coastal areas in Southern Sindh and Balochistan with devastating impacts on the environment South of Karachi, Keti Bander and other parts of the Indus Delta. Studies indicate that a sea level rise of about 2 mm may submerge about 7,500 sq km of the Indus Delta. This rise will affect the coastal industry including power plants, refineries, ports, and tourism. Ultimately, the compound impact of this rise may aggravate seawater intrusion, causing not only loss of productive land but also leading towards increased salinity. At the regional level, it is projected that about 10% area of Bangladesh and a major part of Maldives are likely to be submerged through seawater intrusion by the end of the 21st century.
Glacial Lake Outburst Floods and Landsliding
In Pakistan, the Hindu Kush, Himalayas, and Karakoram glaciers are melting due to increased temperature. It is estimated that about 3,044 glacial lakes have developed in Gilgit-Baltistan and Khyber Pakhtunkhwa.⁴ These lakes increase vulnerability and may become a growing risk for the communities living downstream in the form of glacial lake outburst floods, which facilitate sudden flooding events causing devastating impacts on the socio-economic conditions. During 2010, heavy rainfall triggered massive landslides, heavy rocks fell and blocked the flow of Hunza River for approximately five months. As a result, 20 people lost their lives, about 6,000 villagers were displaced and an area of about 19 km of the Karakoram highway was inundated. In the aftermath of this disaster, a 21 km long and 100 m deep lake known as Attabad Lake was formed.
Change in Precipitation Patterns 
Another evident phenomenon is variability in annual precipitation, which has increased during the last 50 years all over the country. The inter-annual variability in rainfall has increased the reoccurrence frequency of flooding events and Pakistan is experiencing flooding approximately every 3-5 years. The flood of 2010 was a climatic disaster as subtropical jet streams moved downwards to the Northern areas of Pakistan and created a blocking effect when it collided with Northward moving monsoon. It caused heavy rainfall in the Northern areas of the country during the months of July and August. This intensive rainfall persisted for about 24 hours in Peshawar (274 mm), whereas rainfall of about 187 mm was recorded in April 2009. A vast area of Pakistan along the Indus River was affected during the 2010 floods with approximately 2,000 reported deaths.⁵ Due to changing precipitation trends, about 30% less than normal rainfall was recorded during 2018, whereas 45% higher than normal rainfall was reported during winter in 2019. Similarly, in Mithi, Tharparkar, rainfall of 430 mm was recorded in August, 2020 against an annual average of 165 mm. 
Urban Flooding
The disturbance in monsoon pattern due to the changing climate has intensified urban flooding, which has become a recurring phenomenon since 2000 in large cities like Karachi, Lahore, and Rawalpindi. During 2020, Pakistan suffered from heavy rains and flooding in the country, which caused damage to about 200,000 homes and had a life toll of around 400 people.⁶ The urban flooding in Karachi is a recent example where almost 590 mm rainfall was recorded in August, 2020 against an average of 68 mm. This, combined with urbanization, reduction in green belts and vegetative cover and illegal encroachments in natural drains contributed towards catastrophic urban floods. 
Increase in Cyclones
Prolonged hot days are responsible for increased ocean surface temperature, which aid in the generation of cyclones. During 1990-2010, tropical cyclones in the Indian Ocean occurred after every 4 to 5 years. However, the frequency of occurrence of cyclones has gradually increased; about two cyclones per year have been reported in 2019 with consequential losses. In 2007, the tropical cyclone called Yemyin killed about 529 people along the Sindh and Balochistan coastlines. In 2014, cyclone Nilofer resulted in heavy rains in Karachi, whereas, cyclone Tukte caused a massive dust storm along the coastal cities of Sindh followed by significant rainfall in May 2021. 
Increase in Crop Water Requirements
Climate change directly affects the water balance influencing the soil moisture retention, evapotranspiration, precipitation pattern and groundwater storage. Pakistan’s two third area lies in arid regions and rate of evapotranspiration is high. Elevated global temperature will increase evapotranspiration and the loss of water from plants and soil surface will increase aridity of the region. Higher evapotranspiration will increase crop water requirements significantly. Scientific models for crop productivity are used by different researches to evaluate the impact of changing weather on crops. Agronomic crop yield is experiencing a 50% reduction globally.⁷ 
In summer, during Rabi season, when wheat crop is in the grain formation stage, increased evaporation intensifies water requirement and puts additional pressure on the available water resources to meet crop water requirements to get optimum yield. Consequently, early ripening of the crop, affecting both quality of the grain and overall yield has been observed. During Kharif season, Southern part of the country experiences high temperatures. The region also receives some monsoon rainfall, which may help in reducing evapotranspiration. However, the current variability in rainfall pattern is highly influencing cotton yields. A decline of 9% globally and 5% in Pakistan’s production has been observed by crop phenologists.⁸
Food Insecurity and Water Stress 
Temperature and precipitation variability are affecting the global and regional water balance. The spatial shift in precipitation has affected rainfed areas by reduced water availability during cropping season. According to IPCC projections, agricultural productivity in Asia is declining substantially along with an increased occurrence of droughts and floods. Research studies have highlighted a significant correlation of temperature and crop yields; a fall of 6% in wheat productivity is observed for every 1⁰C increase in temperature.⁹ Due to decreased productivity and increasing population, the world is suffering from food shortage. 
Warmer climate also increases water demands for human and animal consumption. Pakistan’s irrigation system depends on the glacial melt and rainfall in the country. For irrigation, major contribution is provided by river inflows. Recurring floods have increased sedimentation with consequent reduction in the storage capacity of large reservoirs raising pressure on groundwater resources to meet supplementary crop water requirement. The current annual per capita water availability being below 1,000 m3 indicates water scarcity. This is an alarming situation leading towards food insecurity.
Threat to Biodiversity and Ecosystems
The climatic implications are also responsible for land degradation and habitat loss for wildlife around the globe and Pakistan is no exception. Studies indicate that turtles that visit beaches along the coast of Sindh and Balochistan to lay eggs are now rarely observed in the region due to anthropogenic impacts like pollution and degradation of habitat caused by climate change. Similarly, persistent droughts in Thar have gravely endangered the livestock of the area. Thar, once home to an estimated 6 million livestock, is facing severe droughts brought about by the changing climate. Resultantly, herds of livestock have fallen prey to droughts and many more are awaiting a similar fate.
Mangroves play as a natural barrier between saline and fresh water but due to an increase in sea level, this natural barrier is under threat. The intrusion of saline water also disrupts the growth of plant species, which grow in mild saline water. The mangrove ecosystem is in danger, as loss of mangrove flora is no more host to the migratory birds and seagulls. The loss of mangroves not only destroys the natural habitat of various species residing within the swamps, but also loss of plants and animals, which are the bread and butter for some communities. If the situation prevails, it will not only destroy the mangrove forest but also facilitate conversion of cultivable land into salt plains.
In a nutshell, climatic variability is a cyclic process, influenced by changes in the natural ecosystem induced by anthropogenic activities. Therefore, the important consideration is minimizing an overall degradation of the ecosystem. For this purpose, afforestation is the best solution for the restoration of the natural environment providing life sustainability on planet Earth. Pakistan is making tremendous efforts in this direction by undertaking mega afforestation projects. 
Increase in Epidemics
Climate change also has a significant impact on temperature related epidemics like dengue and malaria. The rising temperature has a direct relationship with the spread of various vector-based diseases like malaria and dengue. Moist and warm temperatures are host to mosquito breeding in the hilly areas of Islamabad and Potohar plains of Rawalpindi, where coupled with poor hygienic conditions, malaria and dengue cases increase from September to October. 
Effect on the Financial Sector
Climate change has its adverse impacts on the financial sector. Being a cross-cutting theme, water is at the core of sustainable development for economic growth. The Global Climate Risk Index Report (2020) indicates that Pakistan has suffered an economic loss of about USD 3792.52 million due to over 150 extreme weather events during the last couple of decades. 
National and International Obligations
Pakistan has adopted the Sustainable Development Goals (SDGs), not only as internationally binding but also as a national development agenda. The country is also a signatory to the Paris Agreement 2015 that emphasizes reduction in greenhouse gas emissions by 20%. The National Assembly of Pakistan passed a resolution in 2016 for the national implementation of SDG Agenda 2030. After 2018, a national SDG Framework was developed to localize the national action plan for priority SDGs and SDG 13 is one of them. It aims at taking urgent actions to combat climate change and its impacts. The “Reducing Emission from Deforestation and Forest Degradation (REDD+) preparedness” followed by a billion tree tsunami project, are focused efforts being done in the country to combat climate change. The National Climate Change Policy 2012 provides guidelines at the federal level to develop climate resilient plans for socio-economic development.
Conclusion
Climate change or climate variability is a reality now. It affects the whole ecosystem threatening the water, food and energy security. If not managed properly, it has and would have huge impacts on the country’s economy and well-being of the population. Therefore, it is important that all stakeholders – from public to the policymakers – realize its severity and take actions accordingly. One of the greatest initiatives that can help reduce climate change impacts is the “Green and Clean Pakistan” where everybody can play his/her role to effectively minimize the adverse effects of climate change.

The writer is Chairman, Pakistan Council of Research in Water Resources, Islamabad.
E-mail: [email protected]

1. Asian Development Bank, 2017. Climate Change Profile of Pakistan
2. Pakistan Metrological Department. State of Pakistan. Climate in 2020. Available at: http://www.pmd.gov.pk/cdpc/Pakistan_Climate_2020.pdf 
3. Rabbani, A. I., A. R. Tabrez, N. A. Sayed, and S. M. Tabrez. (2008). The Impact of Sea Level Rise on Pakistan’s Coastal Zones – In a Climate Change Scenario. https://doi.org/10.13140/2.1.2353.9203
4. https://www.pk.undp.org/content/pakistan/en/home/projects/Glof-II.html
5. Pakistan floods 2010: Early recovery plan for the health sector, WHO, 2011.
6. https://earthobservatory.nasa.gov/images/147330/extreme-monsoon-rains-in-pakistan 
7. Arshad, A., Raza, M. A., Zhang, Y., Zhang, L., Wang, X., Ahmed, M., and Habib-ur-Rehman, M. (2021). Impact of Climate Warming on Cotton Growth and Yields in China and Pakistan: A Regional Perspective. Agriculture, 11(2), 97. 
8. Ibid
9. Asseng, et al., (2015). Rising temperatures reduce global wheat production. Nature Climate Change, 5(2), 143–147.