9 - GCC I

climate v. weather

weather: the state of the atmosphere at a place and time as regards heat, dryness, sunshine, wind, rain, etc. climate: the composite of generally prevailing weather conditions of a region (includes temperature, air pressure, humidity, precipitation, sunshine, cloudiness, and winds) throughout the year, averaged over a series of years

where is the data coming from?

contemporary: satellites and monitoring stations - measure current trends in climate and greenhouse gases - geological stratification and fossil records - certain organisms only live at certain temperatures - fossil records provides a timeline through geologic time - ratio of radioactive isotopes in sediment - ratio depends of temperature - ice cores - trapped greenhouse gases

Milankovitch cycles

cycle irregularities in the movement of and axial tilt of the Earth around the Sun

global climate change

long-term alteration in global weather patterns - especially increases in temperature and story activity

global climate change is

long-term alteration in global weather patters, especially increases in temperature and story activity

tectonic movement

movement of tectonic plates affect flow of ocean and air currents, chaining climate

weather

short term changes

climate is regulated by complex interactions among component of the Earth system...

- Airborne particulates ("aerosols" ) have a complex effect on Earth's energy balance: they can cause both cooling, by reflecting incoming sunlight back out to space, and warming, by absorbing and releasing heat energy in the atmosphere. - The interconnectedness of Earth's systems means that a significant change in any one component of the climate system can influence the equilibrium of the entire Earth system. Positive feedback loops can amplify these effects and trigger abrupt changes in the climate system.

greenhouse gases

- Carbon Dioxide - a byproduct of many anthropogenic activities - can have a strong insulating effect on the atmosphere - Methane (natural gas extraction and agriculture) and nitrous oxide (industry) are very potent greenhouse gases but have shorter residence times - All serve to refract re-radiated heat back to the Earth's surface (prevents convective cooling) - Natural sources of carbon dioxide (respiration, geological activity, etc.), methane (swamp gas), and nitrous oxide (soil) occur as well... - But, additions of these greenhouse gases leads to additional heat trapping

climate varies over space and time through both natural and human-induced processes

- Climate is determined by long-term patterns of temperature and precipitation averages and extremes at a location. - Climate change is a significant and persistent change in an area's average climate conditions or their extremes. - Scientific data indicate that global climate has changed in the past, is changing now, and will change in the future. - Based on evidence from tree rings, other natural records, and scientific observations made around the world, Earth's average temperature is now warmer than it has been for at least the past 1,300 years.

human activities are impacting the climate system

- Growing evidence shows that changes in many physical and biological systems are linked to human-caused global warming. Some changes resulting from human activities have decreased the capacity of the environment to support various species and have substantially reduced ecosystem biodiversity and ecological resilience. - Scientists and economists predict that there will be both positive and negative impacts from global climate change. If warming exceeds 2 to 3°C (3.6 to 5.4°F) over the next century, the consequences of the negative impacts are likely to be much greater than the consequences of the positive impacts.

anthropogenic influences

- Human alterations to natural cycles has led to a rapid increase in the emission and amount of atmospheric carbon - Causes two problems: - Rate is exceeding the ability of natural systems to adapt - New norm will be that things remain hot

life on Earth depends on, is shaped by, and affects the climate

- Individual organisms survive within specific ranges of temperature, precipitation, humidity, and sunlight. - Small amounts of greenhouse gases in the atmosphere warms Earth's surface, sustaining liquid water and life. - Changes in climate conditions can affect the health and function of ecosystems and the survival of entire species. - Natural records show that the last 10,000 years have been an unusually stable period in Earth's climate history. - Life—including microbes, plants, animals and humans—is a major driver of the global carbon cycle and can influence global climate by modifying the chemical makeup of the atmosphere.

climate change will have consequences for the Earth system and human lives

- Melting of ice sheets and glaciers, combined with the thermal expansion of seawater as the oceans warm, is causing sea level to rise. - Climate plays an important role in the global distribution of freshwater resources. Changing precipitation patterns and temperature conditions will alter the distribution and availability of freshwater resources, reducing reliable access to water for many people and their crops. - Incidents of extreme weather are projected to increase as a result of climate change. These include: heat waves, episodes of severe cold, less frequent but more intense precipitation. - Increasing CO2 levels in the atmosphere is causing ocean water to become more acidic, threatening the survival of shell-building marine species and the entire food web of which they are a part. - Ecosystems on land and in the ocean are disturbed by climate change. Animals, plants, bacteria, and viruses will migrate to areas with favorable climate conditions, invading areas they did not previously inhabit. - Human health and mortality rates will be affected to different degrees in specific regions of the world as a result of climate change.

climate varies over space and time through both natural and human-induced processes...

- Natural processes driving Earth's long-term climate variability do not explain the rapid climate change observed in recent decades. The only explanation that is consistent with all available evidence is that human impacts are playing an increasing role in climate change. - Natural processes that remove carbon dioxide from the atmosphere operate slowly when compared to the processes that are now adding it to the atmosphere.

our understanding of the climate system is improved through observations, theoretical studies, and modeling

- The components and processes of Earth's climate system are subject to the same physical laws as the rest of the Universe. Therefore, the behavior of the climate system can be understood and predicted through careful, systematic study. - Environmental observations are the foundation for understanding the climate system. These include weather instruments and natural records, such as tree rings, ice cores, and sedimentary layers. - Observations, experiments, and theory are used to construct and refine computer models that represent the climate system and make predictions about its future behavior. - Climate scientists' ability to predict climate patterns months, years, or decades into the future is constrained by different limitations than those faced by meteorologists in forecasting weather days to weeks into the future. - Scientists have conducted extensive research on the fundamental characteristics of the climate system and their understanding will continue to improve. Current climate change projections are reliable enough to help humans evaluate potential decisions and actions in response to climate change.

human activities are impacting the climate system

- The overwhelming consensus of scientific studies on climate indicates that most of the observed increase in global average temperatures since the latter part of the 20th century is very likely due to human activities. - Emissions from the widespread burning of fossil fuels since the start of the Industrial Revolution have increased the concentration of greenhouse gases in the atmosphere. - Human activities have affected the land, oceans, and atmosphere, and these changes have altered global climate patterns.

climate is regulated by complex interactions among component of the Earth system

- earth's climate is influence by interaction involving the Sun, ocean, atmosphere, clouds, ice, lands, and life - oceans exert amor control on climate by dominating Earth's energy and water cycles - greenhouse gasses absorb heat energy more efficiently than abundant gases - the abundance of greenhouse gases in the atmosphere is controlled by biogeochemical cycles

the sun is the primary source of energy for Earth's climate system

- much of the sunlight that reaches Earth is absorbed and warms the planet - when Earth emits the same amount of energy as it absorbs, its average temperature remains stable - the title of Earth's axis relative to its orbit around the Sun results in predictable seasonal changes - gradual changes in Earth's rotation and orbit change that intensity of sunlight received in our polar and equatorial regions - satellite measurements taken over the past 30 years show that the Sun's energy output has change only slightly

natural cycles

- tectonic movement - Milankovitch cycles

essential principles of climate science

1) The Sun is the primary source of energy for Earth's climate system. 2) Climate is regulated by complex interactions among components of the Earth system. 3) Life on Earth depends on, is shaped by, and affects climate. 4) Climate varies over space and time through both natural and human-induced processes. 5) Our understanding of the climate system is improved through observations, theoretical studies, and modeling. 6) Human activities are impacting the climate system. 7) Climate change will have consequences for the Earth system and human lives.

anthropogenic influences

Human alterations to natural cycles has led to a rapid increase in the emission and amount of atmospheric carbon Additional emissions leads to rapid heat-trapping effect (2 - 6°C in 100 years) - Causes two problems: - Rate is exceeding the ability of natural systems to adapt - New norm will be that things remain hot

global warming

a gradual increase in the average temperature of the Earth's atmosphere and its oceans

climate

annual and decadal trends