Company lists · Data verified August 2026

Top 25 Climate consulting firms based in the United States

Name: Climate consulting firms based in the United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Verified Aug 28, 2026 2,097 companies tracked

There are 2,097 climate consulting firms headquartered in the United States (RevenueBase, August 2026). RevenueBase tracks 40,041 professional contacts across them, including 19,508 with verified work emails and 14,811 with mobile numbers. New York is the largest hub.

This list covers climate consulting firms headquartered in the United States, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Data current as of August 28, 2026.

2,097Companies

40,041Contacts tracked

19,508Verified emails

14,811Mobile numbers

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The 25 largest climate consulting firms based in the United States

Ranked by team size

Top 25 of 2,097 climate consulting firms based in the United States, ranked by team size, largest first. Data verified Aug 28, 2026. Click a count to unlock that company's people.
#	Company	HQ	Employees	Contacts	Verified emails
1	APTIM	Wichita, KS	1,001-5,000	2,644	1,098
2	Baringa	New York, NY	1,001-5,000	2,198	1,548
3	Ricardo	California, MD	1,001-5,000	2,111	955
4	J.S. Held LLC	Jericho, NY	1,001-5,000	1,924	1,383
5	Swca Environmental Consultants	Phoenix, AZ	1,001-5,000	1,618	1,159
6	Verdantas	Toledo, OH	1,001-5,000	1,127	795
7	Braun Intertec Corporation	Amarillo, TX	1,001-5,000	1,054	691
8	Environmental Science Associates	Petaluma, CA	501-1,000	725	517
9	Inerco	Delaware	1,001-5,000	682	90
10	EBI Consulting	Springfield Township, PA	501-1,000	530	351
11	Natural Power	Seattle, WA	501-1,000	505	349
12	Rincon Consultants	San Diego, CA	501-1,000	483	312
13	Groundwater & Environmental Services, INC	Amherst, NY	201-500	452	229
14	TRIO	Mclean, VA	201-500	382	245
15	P2s	Irvine, CA	201-500	370	208
16	LSA	Roseville, CA	201-500	331	120
17	3degrees Group, INC	San Francisco, CA	201-500	325	216
18	Environmental Consulting & Technology, Inc. ECT	Tampa, FL	201-500	303	176
19	Cascade Energy	Burlington, VT	201-500	290	194
20	Ecology And Environment, INC	Lancaster, NY	5,001-10,000	277	19
21	Illumine-I	Austin, TX	201-500	276	41
22	Nova Group, GBC	St. Louis Park, MN	201-500	264	155
23	PSC Consulting	Westborough, MA	201-500	264	135
24	Kleinschmidt Associates	Pittsfield, ME	201-500	221	154
25	PEG	Fairfax, VA	201-500	211	68

Showing 25 of 2,097 climate consulting firms based in the United States

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Climate consulting firms based in the United States at a glance

As of Aug 28, 2026

1-10Median size (employees)

New YorkLargest hub · 109 HQs

14,811Contacts with mobile numbers

112Emails re-verified in last 30 days

Companies by employee count

1-10

1,437

11-50

491

51-200

113

201-500

501-1,000

1,001-5,000

5,001-10,000

Climate consulting firms by metro

Metro	Companies
Climate consulting firms in New York	109
Climate consulting firms in Washington	73
Climate consulting firms in Houston	63
Climate consulting firms in San Francisco	54
Climate consulting firms in Chicago	48
Climate consulting firms in Denver	48
Climate consulting firms in Seattle	43

How this list was built

Source: The RevenueBase company graph: 21.3 million companies and 398.9 million professional contacts resolved from primary sources.
Inclusion: Companies whose own business descriptions match “climate consulting firms”, with match quality audited by blind human judging, and headquartered in the United States.
Ranking: Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
Verification: Contact records re-verify on a rolling cadence; 112 contacts on this list were re-verified in the last 30 days.
Refresh: Lists are refreshed periodically as the underlying company graph is re-verified. Last verified Aug 28, 2026.

Frequently asked

How many climate consulting firms are there based in the United States?

There are 2,097 climate consulting firms headquartered in the United States as of August 2026 (RevenueBase).

What is the largest company on this list?

APTIM, headquartered in Wichita, tops this list with the largest team on record.

Which city has the most climate consulting firms?

New York leads with 109 headquartered companies, followed by Washington (73) and Houston (63).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 19,508 verified decision-maker contacts tracked across these 2,097 companies.

How current is this list?

The list is refreshed periodically as the underlying company graph is re-verified. It was last verified on August 28, 2026.

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About this data

RevenueBase is a B2B contact data platform. Its company graph covers 21.3 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph, the same data that powers RevenueBase's B2B data products and the free research portal.