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Two key types of interventions: Mitigation

Actions taken to prevent climate change from occurring, such as reducing carbon emissions.

Two key types of interventions: • Adaptation

Actions taken to reduce the impacts of climate change, such as developing new crop varieties or building new water treatment facilities.

Policy • United Nations Framework Convention on Climate Change (UNFCCC)

- Founded at the Earth Summit in Rio de Janeiro, Brazil, in 1992 - Annual convention of world leaders to negotiate global climate change policy. - Next convention: Conference of the Parties (COP) #28: November 30-December 12, Dubai - Most important convention to date: COP21, the Paris Agreement (2015) • Nationally Determined Contributions (NDCs) add up to carbon neutrality by mid-century • Goal: keep warming to 2 degrees C above pre-industrial levels by 2100 - Ideally below 1.5 degrees C

• How do scientists communicate about climate change?

- Is this effective? Why/why not? - What are other ways that they could communicate about climate change? Pros and cons?

Who does the actual writing?

-hundreds of leading scientists IPCC assessments are written by hundreds of leading scientists who volunteer their time and expertise as Coordinating Lead Authors and Lead Authors of the reports. They enlist hundreds of other experts as Contributing Authors to provide complementary expertise in specific areas. The authors may work with Chapter Scientists who cross-check between findings presented in different parts of the report, carry out additional fact-checking, and work on reference management among other things. Chapter Scientists are usually early career scientists

Which of the following statements is true about albedo: a) A high albedo reflects more solar radiation back into space, while a low albedo absorbs more radiation. b) A high albedo absorbs more solar radiation, while a low albedo reflects more radiation out of the atmosphere. c) Albedo is an intrinsic property of a surface that remains unchanged regardless of the direction of the sun or atmospheric composition. d) Albedo is one of the few climate factors that does not contribute to feedback loops. e) All of the above are false.

A high albedo reflects more solar radiation back into space, while a low albedo absorbs more radiation.

What is climate change?

A long-term alteration in the average conditions of a region, such as precipitation or temperature. This differs from weather, which is short-term conditions.

• Who speaks for the climate?

Consider also communication by other stakeholders: media, policymakers, NGOs, celebrities.

How do humans affect the climate?

Emission of greenhouse gases:- Carbon dioxide (CO2): combustion of fossil fuels, production of cement, deforestation, etc. - Methane (CH4): Natural gas leaks, livestock, landfills, agriculture. - Nitrous oxide (N2O): Agriculture, fossil fuels, solid waste.

Forcings can lead to feedback loops:

Example of a negative feedback loop: - Increased temperature increases evaporation→cloud cover, which would increase reflectivity

Forcings can lead to feedback loops:

Example of positive feedback loop: - As temperatures increase, ice caps melt, revealing dark waterrather than bright snow. The former has a lower "albedo" (measure of reflectivity), so more radiation will be absorbed on the earth's surface rather than reflected back out of the atmosphere. So warming leads to more warming. - Another example, more anthropogenic: As temperatures rise, humans use air conditioners more, increasing GHG emissions, which exacerbates the greenhouse effect.

What causes climate change?

Forcings, which fall into four main categories: Tectonic: Driven by the earth's internal heat and its effects on the surface of the earth, like movement of continents and uplift of mountains. Orbital: Direction and distance from sun, over both short (think seasons) and long-term. Strength of the sun: The sun's radiation changes over time (generally increasing over the earth's history), with shorter fluctuations too. • Anthropogenic: Caused by humans.

What is the objective of the IPCC?

IPCC assessments provide a scientific basis for governments at all levels to develop climate related policies, The assessments are policy-relevant but not policy-prescriptive: they may present projections of future climate change based on different scenarios and the risks that climate change poses and discuss the implications of response options, but they do not tell policymakers what actions to take

How much have humans emitted?

Over the last ~250 years, atmospheric CO2 concentrations have increased from 280 parts per million (ppm) to 400 ppm

How is the IPCC governed?

Participation in the IPCC is open to all member countries of the WMO and United Nations. It currently has 195 members. The Panel, made up of representatives of the member states, meets in Plenary Sessions to take major decisions. The IPCC Bureau, elected by member governments, provides guidance to the Panel on the scientific and technical aspects of the Panel's work and advises the Panel on related management and strategic issues

The Anthropocene

Proposed period in planetary history in which humans have become a dominant force in the functioning of the Earth's systems.

What is the relationship between the Intergovernmental Panel on Climate Change (IPCC) and the parties to the UN Framework Convention on Climate Change (UNFCCC)? a) The IPCC is tasked with developing international policy agreements on climate change, while the parties to the UNFCCC compose a scientific body that avoids taking policy positions. b) The IPCC and UNFCCC are different names for the same group of professionals tasked with leading global efforts to understand and respond to climate change. c) The IPCC is a scientific body that studies climate change and avoids taking policy positions, while parties to the UNFCCC are policymakers tasked with developing international agreements on climate change. d) The IPCC and UNFCCC parties are separate institutions that provide competing proposals for how to address climate change. e) None of the above.

The IPCC is a scientific body that studies climate change and avoids taking policy positions, while parties to the UNFCCC are policymakers tasked with developing international agreements on climate change.

What is the confidence interval for the figure on warming from the IPCC AR6 report (WGI)?

The IPCC uses a number of different confidence intervals, or the likelihood that the actual result will fall within the presented range: - Virtually certain: 99-100% probability - Extremely likely: 95-100%- Very likely: 90-100%- Likely: 66-100% - More likely than not: >50-100% - About as likely as not: 33-66% - Unlikely: 0-33%- Very unlikely: 0-10% - Extremely unlikely: 0-5%- Exceptionally unlikely: 0-1%

How is the research conducted?

The IPCC works by assessing published literature...It does not conduct its own scientific research

What is the IPCC?

The Intergovernmental Panel on Climate Change (IPCC) isthe . The IPCC was set up in 1988 by the World Meteorological Organization (WMO) and United Nations Environment Programme (UNEP) to provide policymakers with regular assessments of the scientific basis of climate change, its impacts and future risks, and options foradaptation and mitigation

Is albedo only affected by color?

The albedo of a surface is the fraction of the incident sunlight that the surface reflects...[I]t should be recognized that an albedo is not an intrinsic property of a surface. Instead, for any surface, the albedo depends on the spectral and angular distribution of the incident light, which in turn are governed by atmospheric composition and the direction of the beam of light from the sun

Who works on these issues?

• Independent researchers around the world • Key coordinating body: The Intergovernmental Panel on Climate Change (IPCC)

What does that have to do with climate?

• The greenhouse effect: • These gases trap heat within the earth's atmosphere, increasing global temperatures (and especially, increasing the temperature of the oceans!)