This week marks the beginning of some of the most active and important months in the quest to limit catastrophic climate change. With Climate Week this week, heads of state, country climate negotiators, and average citizens will all begin the final push towards creating a new global climate agreement .
It’s the perfect time to review what the latest climate data and science are telling us about the challenges the world faces. WRI’s CAIT Climate Data Explorer  utilizes the best data available to help answer some of the most important climate policy questions through easy-to-understand graphics.
1) How have greenhouse gas emissions changed over time?
The global picture of emissions has changed significantly over the past 150 years. While the United Kingdom drove emissions during the Industrial Revolution, by the turn of the 20th century, the United States emerged as a large emitter, and the emissions-production landscape has become increasingly global in recent years. Watch the “Past, Present and Future of Carbon Emissions”  below to understand how it started and where emissions might go in the future, or check out the CAIT Historical Data Explorer .
2) Who are the world’s largest greenhouse gas emitters?
Today, the world’s largest emitters are China, the United States and the European Union (28). Together, they account for nearly half of the world’s greenhouse gas emissions. The top 10 GHG emitters contribute 72 percent of global emissions, excluding emissions from land use change and forestry. Explore emissions by countries and sectors through the graphic below.
3) Why do so few countries contribute such a large percentage of global emissions?
Many factors contribute to a country’s total emissions, including, obviously, its population. However, socio-economic factors such as energy use and economic activities are strong indicators of emissions. To learn more about the factors that impact GHG emissions and to explore countries' emissions visually, visit CAIT data on Google's Public Data Explorer .
4) Which activities contribute the most to global emissions?
Greenhouse gas emissions can come from a variety of sources, such as energy production, agriculture, industry or changes in land use. The energy sector—including electricity, transport and manufacturing—drives the majority of emissions globally. The actual breakdown of emissions sources by sector varies from country to country, and should inform the actions countries take to reduce their footprint.
5) What are countries doing to reduce their emissions?
In preparation for the global deal later this year , countries are submitting climate action commitments, called Intended Nationally Determined Contributions, or INDCs .
The CAIT Paris Contribution Map  tracks each INDC as it is submitted to the global community, and allows for easy comparison between countries. It also provides valuable information and gives an easy visual overview of the state of the climate action commitments.
6) How can I understand countries’ climate action commitments?
Country’s climate action commitments vary significantly in the sectors and gasses they cover, as well as their proposed actions, timeframes, and methods of measurement. The CAIT Paris Contribution Map  structures all INDC data into key categories following the GHG Protocol Mitigation Goals standard to make the information more transparent, comprehensible and comparable.
It’s also important to assess how fair  and ambitious  countries’ climate action commitments are, using criteria such as historical and current emissions, state of development, vulnerability and potential for climate action. The CAIT Equity Explorer  is another valuable tool for evaluating commitments by using radar charts to assess countries across a wide variety of indicators.
7) What does U.S. action look like at the state level?
The Environmental Protection Agency’s Clean Power Plan will play a big role  in helping the United States achieve its INDC goal of reducing overall emissions by 26-28 percent below 2005 levels by 2025. Some states have already made significant progress in reducing emissions, especially in the power sector. Between 2005 and 2011, Washington State led the country in reducing its power sector emissions. Learn more about power sector emissions in this blog post  and dive deep into data from all 50 states and the District of Colombia in the CAIT Historical Data Explorer .
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8) What will the emissions from the top emitters look like in 20 years, if they don’t take any additional action?
Emissions projections depend on  a large variety of assumptions, and all emissions projections show potential trajectories, not actual values. The charts below show the projected emissions trajectory of China, United States and India until 2040, as described by various agencies. The data can be found on the CAIT Projections Tool , which spells out the underlying assumptions that go into emissions projections and features projections for major emitters through 2100.
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Create Your Own Stories and Visualizations
The CAIT Climate Data Explorer  allows users to dive deep into the multiple dimensions of climate change policy making. CAIT offers a variety of tools to explore other dimensions of climate policy to find key information, make comparisons and create visualizations. It provides various ways to explore data  for 186 countries and multiple sectors and gases, and includes historical emissions data, an INDC Tracker , an overview of pre-2020 pledges , an Emissions Projections Tool  and an Equity Explorer .