The phrase "accelerate decline" is correct and usable in written English.
You may use it when describing a situation in which the rate of decrease in something increases. For example, "The lack of rain caused an accelerate decline in the lake's water level."
So I commend Peter Preston's trenchant commentary in The Observer in which he forecast that the seven-day Mirror "will merely accelerate decline" and described it as "another botch of despair that has nothing to offer anyone involved, apart from a few more years of shrinking profits".
The combination of rapid climate change and nonnative stressors may accelerate decline of some tree species and inhibit other species from occupying climatically suitable habitat.
Result of WBE demonstrates that alkali sensitivity damage can significantly accelerate decline of oil relative permeability and reduce residual oil saturation, both of which are detrimental for oil recovery of a reservoir.
COPD exacerbations reduced physical activity and frequent exacerbations accelerate decline in activity over time.
The prediction arising from this is that how the body responds to medical illness or trauma has significant impacts on the integrity of the brain and may accelerate decline in function in these individuals in ways that are independent of Aβ.
To prop up the stock market, the government has introduced stiffer new penalties for short selling, a way of betting on falling prices that tends to accelerate declines.
Doing so, the Blueprint argued, would accelerate declines in HIV incidence globally.
Governments seeking to accelerate declines in undernutrition should incentivize the delivery of postgraduate programmes in nutrition, and in particular, Public Health Nutrition.
This decline had an early phase of acceleration followed by a second phase of accelerated decline.
All they could handle was accelerating decline.
A sharply accelerating decline would imply severe economic distress.
