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Complex Science

abstract water drop largeScientific evidence and complex science represent the foundation and the starting point to identify the interdependencies between climate change and the hydrological cycle. According to NASA, the average temperature in 2013 was 14.6 °C (58.3 °F), which is 0.6 °C (1.1 °F) warmer than the mid-20th century baseline. The average global temperature has risen by about 0.8 °C (1.4 °F) since 1880, according to the January 2014 analysis from NASA's Goddard Institute for Space Studies (GISS). Exact rankings for individual years are sensitive to data inputs and analysis methods. Data from NASA's Gravity Recovery and Climate Experiment show Greenland lost 150 to 250 cubic kilometers (36 to 60 cubic miles) of ice per year between 2002 and 2006, while Antarctica lost about 152 cubic kilometers (36 cubic miles) of ice between 2002 and 2005.

The Working Group I contribution to the IPCC Fifth Assessment Report (AR5) addressed the most recent physical science of climate change and provides new scientific evidence, drawing on more extensive observations, greater understanding of climate processes and feedbacks, improved climate models, and a wider range of climate change projections. A large body of evidence supports the conclusion that human activity is the primary driver of recent warming. This evidence has accumulated over several decades, and from hundreds of studies. The first line of evidence is our basic physical understanding of how greenhouse gases trap heat, how the climate system responds to increases in greenhouse gases, and how other human and natural factors influence climate. The second line of evidence is from indirect estimates of climate changes over the last 1,000 to 2,000 years.

The evidence provided by the existing data from complex science is key to addressing the development impacts and the water security implications of climate change. The presence of scientific evidence on the status and extent of climate change impacts on ecosystems, hydrological cycle and human development is a major pillar to prepare for appropriate development responses through the introduction of relevant adaptation and mitigation strategies (see Sub-theme 2: Development Impact). Resources in this section address the wider challenge of interpreting and using climate data in order to plan the development of water resources more effectively.

Image credit: MaRS Discovery District | Flickr

Climate Models and their evaluation
Intergovernmental Panel on Climate Change 2007
Climate models are based on well-established physical principles and have been demonstrated to reproduce observed features of recent climate and past climate changes. There is considerable confidence that Atmosphere-Ocean General Circ...
Summary for policymakers. Climate change 2007: the physical science basis
S. Solomon (ed); D. Qin; M. Manning / Intergovernmental Panel on Climate Change 2007
The Working Group I contribution to the IPCC Fourth Assessment Report describes progress in  understanding of the human and natural drivers of climate change, observed climate change, climate processes and attribution, and estima...
A review of droughts in the African continent: a geospatial and long-term perspective
I. Masih; S. Maskey; F.E.F. Mussá; P. Trambauer / Copernicus Publications 2014
Comprehensive geospatial and temporal review and analysis of prolonged drought events in Africa. Throughout recent history, Africa has been impacted by numerous prolonged droughts; a situation likely to worsen through the impac...