From Kareiva et al (2007) in Science:

“There really is no such thing as nature untainted by people.”
“Instead, ours is a world of nature domesticated…”
“Roughly 50% of the world’s surface has been converted to grazed land or cultivated crops.”
“More than half of the world’s forests have been lost in that land conversion.”
“The whole notion of a ‘virgin rainforest’ may be erroneous, with extensive prehistoric human activity evident in what were once thought to be untouched forests in the Amazon and Congo.”
“As of 1995, only 17% of the world’s land area had escaped direct influence by humans…”
On every continent, humans have eliminated the largest mammals, leaving behind a fauna of smaller species.

Blowback is a term first used by the C.I.A. to label actions that generate unintended consequences. From the same article, some instances of blowback:

Problem Cause

Blighted coastal zones fertilizers

Deadly algal blooms fertilizers

Depleted biodiversity agriculture,industry

Increased pest and pathogen outbreaks monoculture

Wetland loss levees and channelization

Greater damage in severe storms wetlands loss

Simplification of marine system over-fishing

Jellyfish catch = 3x fish catch simplification of marine system

Invasive species trade and commerce

U.S. cost of $ 100 billion invasive species

Destructive wildfires fire control

Vulnerable crops monoculture