Our compute tax.
MailSynth runs on AI, and AI runs on data centers. So every year we give 2.5% of our revenue to NRDC and Earthjustice.
2.5% of revenue
Every year, good year or not
Split evenly between NRDC and Earthjustice
AI isn’t weightless.
MailSynth runs on AI. AI runs on data centers. Data centers use a lot of electricity and water, and a lot of that electricity still comes from burning things.
What one sorted email sets in motion
- An email lands in your inbox
- Ada, our AI assistant, reads it and files it
- A data center does the math
- Power plants and cooling water keep it running
- Some of that power still comes from burning fuel
What our pledge sets in motion
- You pay for MailSynth
- 2.5% of revenue goes out the door
- NRDC and Earthjustice put it to work
- Lawsuits and policy fights for stronger rules
- The goal: cleaner air and protected places, for everyone
That’s a cost. We don’t pay it, everyone does. So we’d rather treat it as a bill we owe than a thing we don’t mention.
We picked NRDC and Earthjustice because both work through law and policy. A single won case can change what an entire industry is allowed to do. For a company our size, that’s the most leverage we can buy.
And it’s growing fast. The IEA expects the world’s data centers to use about twice as much electricity in 2030 as in 2025, with AI driving much of that growth.
Electricity used by the world’s data centers
2.5% of revenue. Every year.
Split evenly between NRDC and Earthjustice. We give from revenue, not profit, so the money goes out whether or not we had a good year.
It grows with us
Every subscriber pays $108 a year, and $2.70 of it goes to climate work. Slide to see what that adds up to as more people join.
Example numbers, not our subscriber count. Based on one inbox at $9 a month per subscriber.
NRDC
The Natural Resources Defense Council, founded in 1970. More than 800 lawyers, scientists, policy experts and other specialists working for clean air, clean water and healthy communities, in court and in government.
About NRDCEarthjustice
A nonprofit environmental law organization, founded in 1971. Its 200+ full-time lawyers take environmental cases to court, and the people and groups they represent don’t pay a cent.
About EarthjusticeSplit evenly between the two.
What this isn’t
It isn’t a carbon offset, and it doesn’t make MailSynth carbon neutral. Our servers still use power. This is money for the people working to change the rules that decide how that power gets made.
Each year we’ll post what we gave, and the receipts, right here.
One subscriber, one year.
A rough estimate of the climate damage from one subscriber’s AI in a year, in dollars, next to what we give.
MailSynth · 1 subscriber · 1 year
Counted this way, we give about 6.2× the damage.
That’s a size comparison, not an offset.
That electricity is about 11 hours of what an average U.S. home uses.
Count carbon using
How we got these numbers
- About 29,200 emails a year (80 a day) land in one inbox. AI sorts each one and writes a short summary, and once a day it writes the digest.
- Each email counts as about half a typical AI prompt (sorting is tiny, the summary is most of it), the digest as 25 prompts, plus 10% for chat with Ada. A typical prompt uses 0.24 watt-hours, 0.26 mL of water and 0.03 g of CO2e, per Google’s August 2025 measurement of Gemini. Not every request we make goes to Gemini, so it’s a stand-in.
- We also run one free-trial inbox for every paying subscriber, so we count two inboxes.
- Damage is priced at the U.S. EPA’s social cost of carbon: $264 a metric ton in today’s dollars (federal agencies stopped using it in 2025). The stricter count swaps Google’s clean-power accounting for the average U.S. grid, 0.35 kg of CO2e per kWh.
- Left out: training the models, your devices, and everything else MailSynth runs. Treat every number here as rough.
Sources: Google, Aug 2025 · Luccioni et al. 2024 · EPA eGRID2023 · EPA social cost of carbon, 2023 · BLS consumer prices · EIA home electricity
Hotter, higher, and still climbing.
Three numbers from the scientists who measure them. Hover or tap the charts to read any year.
+1.47°C
How much warmer 2024 was than 1850–1900. The hottest year in NASA’s record, which goes back to 1880.
The WMO says 2025 was the second or third warmest year on record, depending on the dataset, and that the last 11 years are the 11 warmest. Copernicus says the 12 months through September 2026 averaged 1.5°C above pre-industrial.
Show the numbers as a table
| Year | °C warmer than 1850–1900 |
|---|---|
| 1880 | +0.02°C |
| 1881 | +0.10°C |
| 1882 | +0.08°C |
| 1883 | +0.01°C |
| 1884 | −0.09°C |
| 1885 | −0.14°C |
| 1886 | −0.12°C |
| 1887 | −0.17°C |
| 1888 | +0.01°C |
| 1889 | +0.08°C |
| 1890 | −0.17°C |
| 1891 | −0.03°C |
| 1892 | −0.08°C |
| 1893 | −0.12°C |
| 1894 | −0.11°C |
| 1895 | −0.04°C |
| 1896 | +0.08°C |
| 1897 | +0.08°C |
| 1898 | −0.09°C |
| 1899 | +0.01°C |
| 1900 | +0.11°C |
| 1901 | +0.03°C |
| 1902 | −0.09°C |
| 1903 | −0.18°C |
| 1904 | −0.28°C |
| 1905 | −0.07°C |
| 1906 | −0.03°C |
| 1907 | −0.19°C |
| 1908 | −0.23°C |
| 1909 | −0.29°C |
| 1910 | −0.25°C |
| 1911 | −0.25°C |
| 1912 | −0.18°C |
| 1913 | −0.15°C |
| 1914 | +0.04°C |
| 1915 | +0.05°C |
| 1916 | −0.17°C |
| 1917 | −0.27°C |
| 1918 | −0.11°C |
| 1919 | −0.08°C |
| 1920 | −0.08°C |
| 1921 | +0.01°C |
| 1922 | −0.09°C |
| 1923 | −0.07°C |
| 1924 | −0.08°C |
| 1925 | −0.03°C |
| 1926 | +0.08°C |
| 1927 | −0.03°C |
| 1928 | −0.01°C |
| 1929 | −0.17°C |
| 1930 | +0.04°C |
| 1931 | +0.10°C |
| 1932 | +0.03°C |
| 1933 | −0.09°C |
| 1934 | +0.06°C |
| 1935 | −0.01°C |
| 1936 | +0.04°C |
| 1937 | +0.16°C |
| 1938 | +0.19°C |
| 1939 | +0.17°C |
| 1940 | +0.31°C |
| 1941 | +0.37°C |
| 1942 | +0.25°C |
| 1943 | +0.28°C |
| 1944 | +0.39°C |
| 1945 | +0.28°C |
| 1946 | +0.12°C |
| 1947 | +0.16°C |
| 1948 | +0.08°C |
| 1949 | +0.08°C |
| 1950 | +0.02°C |
| 1951 | +0.12°C |
| 1952 | +0.20°C |
| 1953 | +0.27°C |
| 1954 | +0.06°C |
| 1955 | +0.05°C |
| 1956 | 0.00°C |
| 1957 | +0.24°C |
| 1958 | +0.25°C |
| 1959 | +0.22°C |
| 1960 | +0.17°C |
| 1961 | +0.25°C |
| 1962 | +0.22°C |
| 1963 | +0.24°C |
| 1964 | −0.01°C |
| 1965 | +0.08°C |
| 1966 | +0.13°C |
| 1967 | +0.17°C |
| 1968 | +0.11°C |
| 1969 | +0.24°C |
| 1970 | +0.22°C |
| 1971 | +0.11°C |
| 1972 | +0.20°C |
| 1973 | +0.35°C |
| 1974 | +0.12°C |
| 1975 | +0.18°C |
| 1976 | +0.09°C |
| 1977 | +0.37°C |
| 1978 | +0.26°C |
| 1979 | +0.35°C |
| 1980 | +0.45°C |
| 1981 | +0.51°C |
| 1982 | +0.33°C |
| 1983 | +0.50°C |
| 1984 | +0.35°C |
| 1985 | +0.31°C |
| 1986 | +0.37°C |
| 1987 | +0.51°C |
| 1988 | +0.58°C |
| 1989 | +0.46°C |
| 1990 | +0.64°C |
| 1991 | +0.60°C |
| 1992 | +0.41°C |
| 1993 | +0.42°C |
| 1994 | +0.50°C |
| 1995 | +0.64°C |
| 1996 | +0.52°C |
| 1997 | +0.66°C |
| 1998 | +0.80°C |
| 1999 | +0.57°C |
| 2000 | +0.58°C |
| 2001 | +0.72°C |
| 2002 | +0.82°C |
| 2003 | +0.81°C |
| 2004 | +0.72°C |
| 2005 | +0.87°C |
| 2006 | +0.83°C |
| 2007 | +0.85°C |
| 2008 | +0.73°C |
| 2009 | +0.85°C |
| 2010 | +0.91°C |
| 2011 | +0.80°C |
| 2012 | +0.84°C |
| 2013 | +0.86°C |
| 2014 | +0.94°C |
| 2015 | +1.08°C |
| 2016 | +1.20°C |
| 2017 | +1.10°C |
| 2018 | +1.04°C |
| 2019 | +1.17°C |
| 2020 | +1.20°C |
| 2021 | +1.04°C |
| 2022 | +1.08°C |
| 2023 | +1.36°C |
| 2024 | +1.47°C |
| 2025 | +1.37°C |
Sources: NASA GISTEMP v4, shifted +0.19°C to 1850–1900 as NASA describes · NASA on 2024 · WMO, State of the Global Climate 2025 · Copernicus, September 2026
Then and now
Pick a year. Try the year you were born.
Carbon dioxide
Temperature vs 1850–1900
Waiting is the expensive option.
Carbon dioxide stays in the air for centuries. Every year of delay adds to a bill that someone pays later, usually someone younger.
4.75 mm
How much the sea has risen each year, on average, since 2012. From 1993 to 2011 it was 2.65 mm a year.
WMO, State of the Global Climate 2025About 3×
How much faster the oceans have been soaking up heat since 2005 than from 1960 to 2005. Ocean heat hit a new record in 2025.
WMO, State of the Global Climate 20258 of 10
Of the 10 worst years for glacier loss since 1950, eight have happened since 2016.
WMO, State of the Global Climate 2025$224B
What natural disasters cost the world in 2025, earthquakes included. About half, $108 billion, was insured.
Munich Re, January 2026Why every company, and why this year
The cuts have to be fast
In the IPCC’s 1.5°C pathways, greenhouse gas emissions fall about 43% below 2019 levels by 2030, and 60% by 2035. We don’t think that happens if only governments and giant companies move.
IPCC AR6 Synthesis Report, B.6.1Every bit of warming counts
In the IPCC’s words, “every increment of global warming will intensify multiple and concurrent hazards.” A tenth of a degree avoided is worth paying for now, not later.
IPCC AR6 Synthesis Report, B.1Most companies are small
99.9% of U.S. businesses are small businesses. If climate is left to the big ones, most businesses sit it out. A small pledge from a lot of small companies adds up.
U.S. SBA Office of Advocacy, 2026Steal this pledge
Run a company? Copy this into your handbook. We’d love the company.
Every year, we give 2.5% of our revenue to organizations fighting climate change.
The places worth keeping.
We’re an email company, not ecologists. But everyone here has a place they go to stop thinking about email. These are a few of ours.
Nature is already doing a lot of the work.
Since 1850, oceans, forests and soils have soaked up about half of the carbon dioxide people have put into the air. Keeping wild places wild isn’t just nice scenery. It keeps that carbon sink working.
Source: Global Carbon Budget 2025Want to help? Start here.
Two ways to get involved and two places to give. Each one takes less time than clearing your inbox.
Get involved
Climate Action Network
The world’s largest climate network: more than 2,500 groups in over 130 countries. Its national and regional networks are a good way to find a climate group near you to volunteer with.
Visit Climate Action Network(opens in a new tab)Citizens’ Climate Lobby
Nonpartisan volunteers in hundreds of local chapters who meet with members of Congress about climate policy. They’ll train you.
Join Citizens’ Climate Lobby(opens in a new tab)Donate
NRDC
More than 800 lawyers, scientists, policy experts and other specialists working for clean air, clean water and healthy communities since 1970.
Donate to NRDC(opens in a new tab)Earthjustice
More than 200 full-time environmental lawyers who take cases to court and represent their clients for free.
Donate to Earthjustice(opens in a new tab)We’re not affiliated with any of these groups, and nobody asked us to list them.
Thanks for reading all the way down here.
The MailSynth team
