Measuring Climate Impact
Understanding the key metrics scientists and policymakers use to track climate change, air quality, water health, and biodiversity—and where we stand against our goals.
Data Sources
Paris Agreement charts use verified public data from NASA GISS and NOAA Mauna Loa Observatory.
Current Air Quality is pulled live from the EPA AirNow API sampling 15 major US cities.
Historical trend charts for Clean Air/Water Act show representative data. For granular historical records, the EPA AQS API provides annual statistics back to 1980.
Paris Agreement Metrics
Global Climate Goals
The Paris Agreement's primary goal is to limit global warming to well below 2°C, preferably 1.5°C, compared to pre-industrial levels (1850–1900). Every fraction of a degree matters—0.5°C can mean the difference between manageable adaptation and catastrophic change.
Current trajectory: We're on track for approximately 2.7°C warming by 2100 under current policies.
Global Temperature Anomaly
°C above 1951-1980 baseline (NASA GISS)
Source: NASA GISS Surface Temperature Analysis
Atmospheric CO₂ Concentration
Parts per million (Mauna Loa Observatory)
Source: NOAA/Scripps Mauna Loa Observatory
Global Temperature Anomaly
PrimaryMeasures deviation from the 1850–1900 baseline average. The "headline" metric of climate change.
Atmospheric CO₂
DriverThe "thermostat" of the planet. Measured in parts per million (ppm). Pre-industrial level was ~280 ppm.
Annual Emissions
ActionGtCO₂e (Gigatonnes of CO₂ equivalent). Includes methane, nitrous oxide, and other greenhouse gases.
Clean Air Act Metrics
Atmospheric Health & Air Quality
The Clean Air Act focuses on "Criteria Pollutants" that directly affect human health. These are highly localized—your air quality can differ from a city just miles away. The Air Quality Index (AQI) is the public-facing summary of these measurements.
Current US Air Quality
Loading live data from AirNow API...
Historical Trends (2000–2023)
Data from EPA Air Quality National Summary — showing dramatic improvements since Clean Air Act enforcement
PM₂.₅ National Average
Annual mean (µg/m³) — EPA Air Trends
Source: EPA Air Quality National Summary
Ground-Level Ozone (O₃)
4th highest daily max 8-hr average (ppb) — EPA Air Trends
Source: EPA Air Quality National Summary
Nitrogen Dioxide (NO₂)
Annual mean (ppb) — EPA Air Trends
Source: EPA Air Quality National Summary
Sulfur Dioxide (SO₂)
1-hour 99th percentile (ppb) — EPA Air Trends
Source: EPA Air Quality National Summary
PM₂.₅ & PM₁₀
Fine particulate matter small enough to enter lungs and bloodstream. The most dangerous and widely-tracked air pollutant. Primary component of AQI calculations.
24-hr Standard (PM₂.₅)
≤ 35 µg/m³
Annual Standard
≤ 12 µg/m³
Ground-Level Ozone (O₃)
Primary component of smog. Forms when pollutants from cars and industry react with sunlight. Measured in parts per billion (ppb). Worse on hot, sunny days.
8-hour Standard
≤ 70 ppb
Nitrogen Dioxide (NO₂)
Primarily from vehicle exhaust and power plants. High levels indicate heavy traffic or industrial activity. Contributes to respiratory problems and smog formation.
1-hour Standard
≤ 100 ppb
Sulfur Dioxide (SO₂)
From burning fossil fuels, especially coal. Causes acid rain and respiratory issues. Levels have dropped dramatically since the Clean Air Act's acid rain program.
1-hour Standard
≤ 75 ppb
Check Your Air: Visit AirNow.gov or OpenAQ for real-time air quality data in your area and global comparisons.
Clean Water Act Metrics
Aquatic Health & Water Quality
The Clean Water Act's goal is to make all U.S. waters "fishable and swimmable."Water quality is complex and varies by location and intended use. These metrics provide the most accessible snapshot of watershed health.
Waters Meeting Quality Standards
% of assessed U.S. waters — EPA National Water Quality Inventory
Source: EPA Section 305(b) Reports to Congress
Impaired Waters
Percentage of water bodies failing to meet quality standards for their intended use (drinking, swimming, fishing, etc.).
Goal
0%
Current U.S. avg: ~50% impaired
Nutrient Loading
Nitrogen & Phosphorus levels (mg/L). Main cause of "Dead Zones" and toxic algae blooms. Often from agricultural runoff.
Total Phosphorus Limit
≤ 0.1 mg/L
(varies by water body type)
Dissolved Oxygen (DO)
Fish and aquatic life need oxygen. Low DO levels indicate ecosystem collapse, often caused by nutrient pollution and algae die-offs.
Healthy Level
≥ 5 mg/L
Below 2 mg/L = "Dead Zone"
Check Your Water: Use the EPA's How's My Waterway app to enter any zip code and see the health of your local watershed.
Living Planet Index
Biodiversity & Ecosystem Health
The Living Planet Index (LPI) tracks the average change in population size of thousands of vertebrate species worldwide. It's increasingly used alongside climate metrics because climate change isn't just about heat—it's about the collapse of biological systems that support human life.
A declining LPI suggests that even if we meet "Net Zero" carbon goals, we may still be losing the "infrastructure" of nature—pollinators, food chains, and ecosystem services we depend on.
Global Living Planet Index
Average vertebrate population change since 1970
-69%
as of 2022 report
What this means: Wildlife populations have declined by an average of 69% in just 50 years. Freshwater species (-83%) and tropical regions are hit hardest.
Source: WWF Living Planet Report — Updated every two years with data from the Zoological Society of London.
Why Track These Metrics?
Accountability
Metrics create measurable goals. Without numbers, it's impossible to know if policies are working or if leaders are keeping their promises.
Early Warning
Trends in these metrics can warn us of problems before they become crises—allowing time for policy interventions.
Informed Voting
Understanding the data helps you evaluate candidates' environmental claims and hold elected officials accountable.
Global Context
Climate change is global. These metrics let you compare your country's progress against international goals and other nations.
Take Action
Your representatives vote on climate policy, EPA funding, and environmental regulations. Find out who represents you and how they've voted on environmental issues.