Climate change has had a number of impacts on the US state of Montana. Heat waves are becoming more common, snow is melting earlier in the spring, and trees are dying as a result of drought, forest fire, and increased prevalence of forest insects. In the next few decades in Montana, climate change is most likely to impact water availability, agricultural yields, and wildfire risk. State and local governments have taken legislative steps, such as establishing a renewable energy portfolio and creating climate action plans, to mitigate the effects of climate change. Impacts Water resources According to the IPCC, possible effects on water systems for the Montana region include less water available in some areas. Warming in mountain states is projected by the IPCC to cause decreased snowpack, more winter flooding, and reduced summer flows. This may increase competition for water resources. Montana is a headwater state, and consequently, potential climate change effects that impact Montana's water resources reach far beyond the state borders. The Department of Environmental Quality, Montana, has determined that climate change will affect essential water resources in Montana as water quality and ecosystems may be compromised when contaminants and sediment are carried by spring run-off at unnatural times. A report from the University of Lethbridge found climate change may alter stream flow and water supply volume by lowering snowpack which may cause low reservoir storage in the spring and dangerously low flows in the summer making perennial streams potentially intermittent. The Montana Wildlife Conservation Society is concerned that warming water may also change patterns of some species such as native bull trout require colder water than other fish and would have a difficult time surviving if waters warmed. Forest resources Montana's forests sequester up to 23.1 million metric tons of carbon dioxide equivalents annually—approximately 62 percent of the state's gross emissions. The state also contains 8.9 million acres thought suitable for afforestation with a potential sequestration capacity of up to 15 million metric tons. The impacts of climate change upon Montana's forests could result in feedback: assuming a shift to a 'drier' precipitation and temperature scenario, the sequestration capacity of Montana's high-elevation forests could be reduced or even eliminated entirely. Agriculture The effects of climate change on agriculture varies among regions and Montana's agricultural production may not change substantially as global temperatures continue to increase over the short term according to the IPCC Fourth Assessment Report.