Xiuhtezcatl Martinez

Earth Guardians is an environmental activist organization founded in 1992.[14] Martinez served as the Youth Director through 2019, transitioning to co-Youth Director alongside Marlow Baines, who assumed the youth leadership role in 2020.[15][8][16][17][18] Earth Guardians' mission is to "inspire and train diverse youth to be effective leaders in the environmental, climate and social justice movements. Through the power of art, music, storytelling, civic engagement, and legal action, we're creating impactful solutions to some of the most critical issues we face as a global community."[19] They work to organize climate strikes, cultivate environmentally focused policy, and encourage individual activism through promoting voting registration.

In 2015, Martinez and 21 other youths filed a lawsuit against the US Federal government, Juliana et al. v United States et al. They argue that the federal government is denying their constitutional right to life, liberty and property by ignoring climate change. The plaintiffs also included parties from the fossil fuel industry as defendants in the lawsuit, but said parties were removed as defendants during pre-trial proceedings. The plaintiffs range in age from 9 to 20 and ten of the children have either Black or Indigenous backgrounds. The lawsuit was launched while Obama was still in office, but in 2017 the plaintiffs substituted Trump's name for that of the former president.[20]

In 2018, he and 13 other youths filed another lawsuit, this time against the state government of Colorado. He is the lead plaintiff in this Martinez v. Colorado Oil and Gas Conservation Commission case. The lawsuit was dismissed by King County Superior Court Judge Michael Scott on January 14, 2019,[21] with the caveat, that the plaintiff and all other companies undertaking the same business of fossil fuel development and production follow the law and its intent, as laid out in the Colorado Oil and Gas Conservation Act (COGCA), which says that the Commission is required "(1) to foster the development of oil and gas resources, protecting and enforcing the rights of owners and producers, and (2) in doing so, to prevent and mitigate significant adverse environmental impacts to the extent necessary to protect public health, safety, and welfare, but only after taking into consideration cost-effectiveness and technical feasibility". Subsection 2 of the COGCA, is thought to be a possible target for future lawsuits and legislative changes, as in the case where local production costs overshoot regional costs or in the case where the public will turn away from local fossil fuel development and production. These factors coupled with decreased demand for fossil fuels are being closely watched by various think tanks and industry and environmental watchdog groups for the next steps in what may be a dynamic set of legal challenges within the state of Colorado.[22]

In December 2018, Remezcla named Martinez in their list of "30 Latinxs Who Made an Impact in Their Communities in 2018".[23]

In April 2019, Martinez wrote an op-ed in Teen Vogue endorsing Bernie Sanders for president, stating, "I believe Bernie Sanders has our back on climate change".[24] In December 2018, Martinez spoke with Sanders at a town hall event called "Solving the Climate Crisis".[25]