If 19.75% of the electorate switched to the party with the best climate policy that could win in their seat, the next general election result would look something like this:

Labour: 3 seats short of a majority
Green: 95 seats short of a majority

Methodology:

Start from VoteClimate's Forecast For The Next General Election where the vote shares (GB) are Labour: 44% | Conservative: 27% | Liberal Democrat: 11.3% | Green: 6.8% | Reform: 6.1%.
Subtract 19.75% from each party's votes in this seat.
Add 19.75% of the electorate to the party with the best climate policy that can win.
For this example, we've estimated that the parties rank on climate policy best to worst as follows:
Green, Plaid Cymru, Liberal Democrat, Labour, SNP
NB: it's implicit in this methodology that VoteClimate can persuade 19.75% of people who might not otherwise have voted to Vote Climate.

Labour just lose their majority with the Greens by far the 2nd-largest party. The Tories and SNP are completely wiped out.

But 19.75% of the electorate is 9 million people.

We need a more radical, more achievable plan... See What If 4.25% Of The Electorate Switch From Labour To A Party With Better Climate Policy?.

[Last updated: September 2023]

If people switch votes as per above, the seats would transfer between parties as follows:

Number of Seats	Switch from Party	To Party
139	Conservative	Green
65	Labour	Green
24	Labour	Liberal Democrat
19	Conservative	Liberal Democrat
17	SNP	Green
14	Conservative	Labour
11	SNP	Liberal Democrat
9	SNP	Labour
5	Labour	Plaid Cymru
5	Liberal Democrat	Green
2	DUP	Green
1	Other	Green
1	Sinn Fein	Green

What If 19.75% Of The Electorate Switch To The Party With The Best Climate Policy That Can Win In Their Seat?