microthermal
/ˌmʌɪkrə(ʊ)ˈθəːml/Ecology
adjective
1 Science. Of, relating to, or involving small quantities of heat.
2Of a climate: cool temperate; characterized by cold winters and short summers. Of an organism: inhabiting such an environment.
Origin
Early 20th century (in an earlier sense). From micro- + thermal.