causes of the climate change, ways of taking care of ecology its disparate impact in the environment around you and worldwide.
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Abstract
Recent climate‐change research largely confirms the impacts on US ecosystems identified in the 2009 National Climate Assessment and provides greater mechanistic understanding and geographic specificity for those impacts. Pervasive climate‐change impacts on ecosystems are those that affect productivity of ecosystems or their ability to process chemical elements. Loss of sea ice, rapid warming, and higher organic inputs affect marine and lake productivity, while combined impacts of wildfire and insect outbreaks decrease forest productivity, mostly in the arid and semi‐arid West. Forests in wetter regions are more productive owing to warming. Shifts in species ranges are so extensive that by 2100 they may alter biome composition across 5–20% of US land area. Accelerated losses of nutrients from terrestrial ecosystems to receiving waters are caused by both winter warming and intensification of the hydrologic cycle. Ecosystem feedbacks, especially those associated with release of carbon dioxide and methane release from wetlands and thawing permafrost soils, magnify the rate of climate change.
Climate fundamentally controls the distribution of ecosystems, species ranges, and process rates on Earth. As a component of the US National Climate Assessment, to be released in 2014, a group of over 60 ecological experts from academic, governmental, and nongovernmental organizations assessed the state of knowledge about how climate change has affected and will affect species, biodiversity, and ecosystem structure, function, and services in the US. Here, we summarize key findings on the impacts of climate change on ecosystems, focusing on the fluxes of matter and energy and the biotic and abiotic parts of ecosystems that contribute most to those fluxes.
In a nutshell:
Recent research confirms that climate change is altering the structure and function of aquatic and terrestrial ecosystems in the US and identifies mechanisms for those impacts
Rising temperature, changes in seasonality, increased frequency and magnitude of extreme events, and acceleration of the hydrologic cycle will shift ecosystem types, process rates, and connections to other ecosystems, often irreversibly
Changes in ecosystem productivity, food‐chain relationships, disease spread, pollutant transport, and climate feedbacks have important societal consequences
The human and financial costs of climate change in the US are so high – equivalent to hundreds to thousands of human lives and tens to hundreds of billions of dollars – that many businesses and government agencies now incorporate climate‐change‐related considerations into their plans and actions
Ecosystem patterns and processes, such as rates of primary productivity or input–output balance of chemical elements, respond in complex ways to climate change because of multiple controlling factors. For example, whether a forest is a carbon (C) source or sink depends on the balance of primary production and ecosystem respiration, processes that respond to different drivers. Physical changes in ecosystems – for instance, changes in thermal stratification patterns in lakes and oceans, flood and drying regimes in streams and rivers, or intensification of the hydrologic cycle across large basins – lead to changes in ecosystem structure and function that have economic and human consequences. Often the extremes or changes in timing have greater impact than changes in average conditions and incur greater societal impacts and costs. Recognizing these issues, climate‐change action plans and management strategies have begun to account for forecasted changes in extremes or seasonality.
Seven key impacts
Although climate change is affecting US ecosystems in numerous ways, seven findings emerged from our assessment as representing the most critical climate‐change impacts on ecosystem structure and function in the US, supported by compelling evidence from the past 4 years (Figure 1). Only a few of the important references can be cited in this article due to space limitations, and we refer readers to the WebReferences for additional supporting references.
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Figure 1
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Climate effects on sea ice, lakes, and coastal ecosystems
The late summer extent of Arctic sea ice continues to decline, with a record low set in 2012 (www.climate‐watch.noaa.gov/article/2012/arctic‐sea‐ice‐breaks‐2007‐record‐low). This low extent exceeds the previous record set in 2007 (Figure 2a). The Arctic Ocean is