why does temperature change during the seasons
As the Earth orbits the sun every 365 days, the axis is always pointing in the same direction into space with the North Pole toward Polaris, the North Star. Around June 21st, the northern hemisphere is angled towards the sun, and receives the most direct radiation and the most energy. This is the start of summer in the northern hemisphere and winter in the southern hemisphere. Six months later, in December, the Earth has made half a revolution around the sun. The northern hemisphere is now angled away from the sun and receives less energy than the southern hemisphere; this is the beginning of winter in the northern hemisphere, and summer in the southern hemisphere. From north to south the results of the distribution of solar energy can be seen in the changing vegetation (see this
), animal behaviors, and by examining the clothes people wear. The growing seasons are shifting. Spring is arriving earlier, winters are shorter, and the number of freezing days is declining. These changes affect the timing of many life cycle events, such as when flowers bloom or when pollinators emerge. Changes in the timing of these events Б spring thaw or songbird migration, for example Б can have adverse effects on ecosystems, because different species may respond to different environmental cues, resulting in a misalignment between species that may rely on one another. How are Seasons Shifting?
Shifting seasons are directly linked to warmer global temperatures. A slight change in temperature is enough to push the spring thaw earlier, and delay the first frost until later in the fall. These environmental changes cause many trees and spring wildflowers to bloom earlier than typical. As a result, winters are shorter, spring is earlier, summers are longer and fall arrives later. The US EPA uses reflecting national phenology trends to indicate climate change. Scientists have high confidence that the earlier arrival of spring events is linked to recent warming trends in global climate. Disruptions in the timing of these events can have a variety of impacts on ecosystems and human society. For example, an earlier spring might lead to longer growing seasons, more abundant invasive species and pests, and earlier and longer allergy seasons. Unusually warm weather in late winter can create a Бfalse springБ that triggers the new growth of plants to begin too early, leaving them vulnerable to any subsequent frosts Б trends that have been increasingly observed throughout the United States. Potential misalignment between lifecycle events of species that rely on one another. Greater risk of frost damage. The earlier arrival of warm temperatures may cause many trees and flowers to blossom earlier, however, the risk of frost lingers. Since some plants are highly vulnerable to frost damage, this can significantly impact the fruit, nut, or seed production of frost-affected plants.
Increased risk of drought, due to the earlier timing of snow-melt and the longer duration of summer. Pests and diseases may have a greater impact, because they will begin feeding and breeding earlier in the season. Some pest species will also increase in numbers due to milder winters, which allow more individuals to survive until spring. Shifting seasons are also a trigger for other climate change impacts, such as: These changes can have profound impacts on species and ecosystems, as well as the human communities that depend on these systems for their ecosystem services. Cooperatively Working Towards Conservation Goals. Land trusts are responding to shifting seasons in various ways. Some groups are beginning to include more plant diversity in restoration projects in order to provide native fauna with other food sources and habitats as the timing of seasons change. In addition to employing to reduce risks and enhance resilience, some land trusts are also supporting efforts to to reduce the extent of future climate change. Land trusts must determine the right planning approach for their organization, however, more and more, conservation organizations are working with their communities to identify opportunities to reduce vulnerabilities and prepare for changing temperatures.
Agencies are making similar strides to implement projects that reduce risks and plan for resilience by incorporating adaptation, mitigation, and engagement into their strategic goals and objectives. For example, the U. S. Fish and Wildlife ServiceБs Strategic Plan for Responding to Accelerating Climate Change identifies seven planning and development goals to support sustainable landscapes. Conservation groups are increasingly partnering with agencies as well as other nonprofits and for-profit organizations to respond to this global challenge at local levels. Building resilience for multiple management objectives. Resilience describes the ability of a system to persist through extreme change. By working to identify and reduce potential threats land managers can and achieve multiple management objectives. is a critical step in the process that helps land trusts identify key threats to resources. enables conservation practitioners to implement interventions to reduce vulnerabilities and to monitor and revise strategies as new information becomes available. There is no one-size-fits-all solution to addressing management challenges associated with warming average temperatures, however, planning that acknowledges vulnerabilities can help land trusts better achieve their conservation objectives. , Nature, EPA, National Phenology Network
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